Tatiana Rochat

Frédérique Lartigue

Elena Disconzi

Rémy A Bonnin

Yiqin Deng

Audrey Vingadassalon

Wang Ji

Ngoc An Nguyen

Florence Lorieux

Wenfeng Liu

Claire Poyart

Constantin Hays

Erwrin Van Dick

Yan Jaszczyszyn

Claude Thermes

Claire Toffano-Nioche

Thuong Van

Du Tran

Maude Guillier

Francis Repoila

Brice Felden

Thao Nguyen

Le Lam

Chantal Bohn

Philippe Bouloc
email: philippe.bouloc@u-psud.fr

Competition experiments with regulatory RNA gene mutants in Staphylococcus aureus: identification of a 3'UTR contributing to optimal growth at low-temperatures

Keywords: Staphylococcus aureus, fitness, sRNA, phenotype RNase III, toxin/antitoxin system, phage, RNA decay, Staphylococcus aureus

FIGURES AND TABLES

 . aureus.........................................................................

I. Staphylococcus aureus 1. General features

In the second half of the nineteenth century, the Scotland surgeon Sir Alexander Ogston identified for the first time the bacterium Staphylococcus from a patient knee abscess joint [START_REF] Ogston | On Abscesses[END_REF]. In 1884, based on pigmented colony types, the German physician and microbiologist Friedrich Julius Rosenbach renamed this bacterium

Staphylococcus aureus to differentiate it from Staphylococcus albus, which is now called

Staphylococcus epidermidis.

Staphylococcus aureus (in Greek Staphylo "bunch of grapes" and in Latin aureus "golden") is a Gram-positive coccal (spherical) bacterium member of the Staphyloccaceae family (Figure 1). This bacterium is non-motile, non-spore-forming, facultative anaerobic and grows in oxygenated conditions or ferments glucose to produce mainly lactic acid. Its colonies are fairly large, round, golden-yellow on rich medium and have a -hemolytic activity on blood agar plates. S. aureus is positive for catalase (decomposes hydrogen peroxide to water and oxygen), reduces nitrate to nitrite and ferments mannitol (in contrast to S. epidermidis).

S. aureus produces a membrane-associated coagulase, with reacts with prothrombin in the blood to form staphylothrombin. This complex triggers blood clotting by converting soluble fibrinogen to insoluble fibrin and may protect the bacteria from phagocytosis [START_REF] Tortora | Microbiology: An Introduction (11th Edition)[END_REF]. S. aureus is negative for urease.

S. aureus reproduces by binary fission. After division, the daughter cells often remain attached, generating bacterial clusters. S. aureus has a circular chromosome of 2.8 M base pairs (bp) with a low GC composition (32.8%). The genome has about 2700 coding sequences of which approximately 38% have unknown function.

Role in disease

S. aureus is one of the most common causes of hospital-acquired (nosocomial) and community-acquired infection. It causes disease by three main mechanisms: (1) invasion of tissues and inflammation, ( 2) toxin production and (3) biofilm formation. S. aureus expresses a large number of virulence factors that include:

Surface proteins, invasion factors (e.g., leukocidin, kinases, hyaluronidase).

Structures for evading phagocytes such as surface factors (e.g., capsule, protein A), biochemical compounds and enzymes (e.g., carotenoids, catalase, lipase, lactamase) or immunological disguises (e.g., coagulase, protein A).

Membrane-damaging toxins, exfoliatin toxins and superantigens.

S. aureus is an important cause of death and morbidity in humans. Carriage rates of S.

aureus may vary between human populations and different studies but can be divided in three types of population: non-carriers (approximately 20% of the population); persistent carriers (20-25%) and intermittent carriers (55-60%) [START_REF] Lindsay | Staphylococcus: Molecular Genetics[END_REF]. In human, S. aureus primarily colonizes the nasal passage and axillae and can occasionally be found as part of the flora of the digestive and vaginal tracts [START_REF] Williams | Healthy Carriage of Staphylococcus Aureus: Its Prevalence and Importance[END_REF]. When the protective layer of the human epithelium is breached and the mechanisms of host immunity fail, the bacterium is able to colonize a wide range of different organs. Most common infections caused by S.

aureus are skin and soft tissue lesions such as boils, styles, and furuncles. However, when this bacterium enters the bloodstream, it can cause more serious and life-threatening infections such as pneumonia (lung infection), endocarditis (inflammation of the heart inner layer, the endocardium), osteomyelitis (infection and inflammation of bone or bone marrow)

or thrombophlebitis (inflammation of veins caused by blood clots), urinary tract infections, bacteremia (presence of bacteria in the blood), sepsis (whole body inflammation cause by an infection) (Figure 2). (From http://www.tjclarkinc.com/bacterial_diseases/hold/staphylococcus.htm).

S. aureus produces enzymes and toxins that are also responsible for food poisoning, toxic shock syndrome and scalded skin syndrome (Figure 2). Food poisoning is caused by eating food contaminated with enterotoxins released by the bacteria rather than by its infection. Toxic shock syndrome is caused by the release of a toxic shock syndrome toxin (TSST, 22 kDa superantigens) into the bloodstream leading to high fever, vomiting, diarrhea, low blood pressure and potentially to death. Scalded skin syndrome occurs mainly in children under 5-year-old, especially newborn babies; it is due to exotoxins (exfoliatin A and B) that cause skin damages. S. aureus is also a substantial pathogen for animals, transmitted between species, and consequently, a worrying zoonotic agent [START_REF] Mcevoy | Decreased Vancomycin Susceptibility in Staphylococcus Aureus Caused by IS256 Tempering of walKR Expression[END_REF]. S.

aureus can overwhelmingly colonize a variety of animals leading to infections in about three percent of the cases [START_REF] Schukken | CNS Mastitis: Nothing to Worry About?[END_REF]. This bacterium is one the main causes of mastitis in cow (inflammation of udder) in the dairy industry with an infection rate up to 10 to 12 percent [START_REF] Tenhagen | Prevalence of Pathogens in Milk Samples of Dairy Cows with Clinical Mastitis and in Heifers at First Parturition[END_REF]).

Antibiotic resistance

S. aureus has the potential to become resistant to multiple antibiotics, complicating significantly its treatment [START_REF] Uhlemann | Evolution of Community-and Healthcare-Associated Methicillin-Resistant Staphylococcus Aureus[END_REF]). In the 1940s, the first treatment against S.

aureus infections was penicillin. Unfortunately, S. aureus developed quickly resistances to this antibiotic due to the presence of penicillinase (a form of -lactamase) that degrades penicillin. Two decades later, more than 80% of hospital-and community-acquired S. aureus isolates were penicillin-resistant.

In 1959, methicillin, the first semi-synthetic penicillinase-resistant penicillin, was used in clinical treatments. Two years later, the first case of methicillin-resistant S. aureus (MRSA) was reported. Other antibiotics from the same group such as oxacillin, cloxacillin, dicloxacillin, flucloxacillin and nafcillin were developed to replace methicillin, but S. aureus strains became extensively resistant to all -lactam antibiotics due to the emergence of a penicillin binding protein 2 (PBP2) having a decrease binding affinity for penicillin.

Glycopeptide antibiotics, including vancomycin, are the most efficient weapons against Gram-positive infections, including the problematic MRSA strains. The existence of vancomycin-resistant S. aureus (VRSA) that are already MRSA is a serious threat in human health since it could lead to a therapeutic dead-end [START_REF] Zetola | Community-Acquired Meticillin-Resistant Staphylococcus Aureus: An Emerging Threat[END_REF]. In industrialized nations, 20-60% of all hospital S. aureus strains are methicillin-resistant (Hospital-acquired MRSA, HA-MRSA), and newly emerging community-acquired MRSA (CA-MRSA) combine antibiotic resistance with hyper-virulence. In 1999, it was reported that about 500,000 patients of United States hospitals were infected every year by S. aureus [START_REF] Bowersox | Experimental Staph Vaccine Broadly Protective in Animal Studies[END_REF].

The genome of MRSA strains carry SSCmec mobile genetic elements containing the mecA gene that confer resistance to methicillin and all other β-lactam antibiotics [START_REF] Katayama | A New Class of Genetic Element, Staphylococcus Cassette Chromosome Mec, Encodes Methicillin Resistance in Staphylococcus Aureus[END_REF]. In addition, CA-MRSA strains not only have a short SCCmec but also a Panton-Valentine leukocidin locus [START_REF] Vandenesch | Community-Acquired Methicillin-Resistant Staphylococcus Aureus Carrying Panton-Valentine Leukocidin Genes: Worldwide Emergence[END_REF].

S. aureus can acquired resistance against virtually all antimicrobial agents available in hospitals and communities [START_REF] Deleo | Community-Associated Meticillin-Resistant Staphylococcus Aureus[END_REF]). However, a new cell wall inhibitor named teixobactin was recently reported as an efficient antibiotic for Gram-positive pathogens including drug-resistant strains [START_REF] Ling | A New Antibiotic Kills Pathogens without Detectable Resistance[END_REF]. Teixobactin binds to motifs of lipid II and lipid III, which are precursor of peptidoglycan and cell wall teichoic acid, respectively and hence inhibits cell wall synthesis. So far, no resistant S. aureus strains with teixobactin were observed.

II. Overview of adaptation and virulence in S. aureus 1. Some examples in adaptation

Adaptation to environmental changes is a crucial step for survival and development.

Most bacteria adapt to new conditions by changing genes expression including those encoding structural proteins, transporters and metabolic enzymes. The success of S. aureus as a virulent pathogen is due to its ability to respond to change in different environments. It tolerates dry conditions, nutrient deprivation and survives on different external surfaces [START_REF] Oie | Survival of Methicillin-Resistant Staphylococcus Aureus (MRSA) on Naturally Contaminated Dry Mops[END_REF][START_REF] O'connell | Intensive Care Unit Design and Environmental Factors in the Acquisition of Infection[END_REF]. It can also grow in a variety of media within a broad range of temperatures (from 15 o C to 45 o C, optimal 37 o C), pHs (acidic to alkaline) and high salt conditions (concentration up to 15 percent) [START_REF] Bore | Acid-Shock Responses in Staphylococcus Aureus Investigated by Global Gene Expression Analysis[END_REF]).

Dissecting the transcriptional adaptation of S. aureus is central for understanding how this pathogen interacts with its various hosts and is able to cause life-threatening diseases. This chapter will present a few examples of S. aureus adaptation, which are reminiscent of conditions found during host infection.

Oxygen limitation

S. aureus transiting between hosts or when living on the skin is in an aerobic environment but when growing in an abscess, the oxygen concentration is limited. S. aureus which is a facultative anaerobe that respires with or without oxygen has to sense the oxygen level and adapts its response accordingly. Transcriptomes and proteomes were performed in anaerobic conditions in strain COL to investigate the influence of oxygen on S. aureus global gene expression (Fuchs et al. 2007). In limited oxygen conditions, 130 genes were upregulated and 77 genes were downregulated. As expected, many genes belonging to the glycolysis, fermentation and anaerobic pathways showed an increase of expression.

Moreover, some virulence factor genes were also upregulated such as pls, hlY, splCD, epiG, isaB. On the other way, many genes encoding ribosomal proteins, tRNA synthesis, elongation factor G and enzymes involved in the tricarboxylic acid (TCA) cycle, decrease their transcription.

SrrAB (Staphylococcal respiration response) [or SrhSR (Staphylococcal resDE homologues)] was the first oxygen sensor system discovered in S. aureus. It is a twocomponent system (TCS) in which SrrB is a membrane sensor and SrrA is a cytoplasmic response regulator [START_REF] Throup | The srhSR Gene Pair from Staphylococcus Aureus : Genomic and Proteomic Approaches to the Identification and Characterization of Gene Function[END_REF][START_REF] Yarwood | Identification of a Novel Two-Component Regulatory System That Acts in Global Regulation of Virulence Factors of Staphylococcus Aureus[END_REF]. It is homologous to the ResDE aerobic/anaerobic regulation system from Bacillus subtilis. The srrAB mutant had a growth defect in anaerobiosis while no phenotype was observed in aerobic condition. The transcriptome analysis of wild-type and srrAB strains grown in aerobic and micro-aerobic condition indicate that the expression of regulatory RNA RNAIII and spa (encoding the protein A) genes (see chapter IV.3 for more details) increase in srrAB mutant under microaerobic conditions. In addition, the SrrAB system is involved in nitrosative (NO) and hypoxia stress response [START_REF] Kinkel | The Staphylococcus Aureus SrrAB Two-Component System Promotes Resistance to Nitrosative Stress and Hypoxia[END_REF]). Various srrAB-required genes that were found to vary during two stress conditions are involved in cytochrome and heme biosynthesis, anaerobic metabolism and NO-detoxification.

SrrAB depletion affects the expression of genes involved in the TCA cycle, in fermentation and energy, arginine catabolism, xanthine catabolism and cell morphology [START_REF] Throup | The srhSR Gene Pair from Staphylococcus Aureus : Genomic and Proteomic Approaches to the Identification and Characterization of Gene Function[END_REF]. It also impacts biofilm formation and increases cell death. It has been proposed that SrrAB links the oxygen response to the regulation of virulence factors [START_REF] Yarwood | Identification of a Novel Two-Component Regulatory System That Acts in Global Regulation of Virulence Factors of Staphylococcus Aureus[END_REF]. Indeed, the srrAB mutant has an attenuated virulence in a murine model for hematogenous pyelonephritis infection as compared to a wild-type strain [START_REF] Throup | The srhSR Gene Pair from Staphylococcus Aureus : Genomic and Proteomic Approaches to the Identification and Characterization of Gene Function[END_REF].

Under anaerobic condition, the response regulator SrrA-P binds to a 100 bp DNA sequence located in the upstream region of the ica gene to activate the production of polysaccharide intercellular adhesin (PIA). PIA is an important cell surface factor that protects S. aureus against human neutrophils [START_REF] Ulrich | The Staphylococcal Respiratory Response Regulator SrrAB Induces Ica Gene Transcription and Polysaccharide Intercellular Adhesin Expression, Protecting Staphylococcus Aureus from Neutrophil Killing under Anaerobic Growth Conditions[END_REF]. Therefore, the SrrAB TCS plays a positive role in PIA production helping bacterial survival against human defense mechanisms. A model of SrrAB activity is presented in figure 3. The second oxygen sensor system discovered was the TCS NreBC (Nitrogen regulation) present in some staphylococci such as S. aureus, S. epiderminis, S. carnosus [START_REF] Kamps | Staphylococcal NreB: An O2-Sensing Histidine Protein Kinase with an O2-Labile Iron-Sulphur Cluster of the FNR Type[END_REF]. NreB is a cytoplasmic oxygen sensor containing an O 2 -labile iron-sulfur cluster considered as equivalent to the FNR (Fumarate and Nitrate reductase Regulatory) sensor, while NreC is a response regulator that controls gene expression involving in nitrogen regulation. In the presence of iron and low oxygen level, iron-sulfur cluster is formed and NreB autophosphorylates itself. Then, the active form NreB-P transfers its phosphoryl group to the response regulator NreC and activates it. NreC-P then positively controls the expression of the nitrite reductase (nir) operon , nitrate reductase (narGHJI) operon and narT (nitrate transporter) gene. On the contrary, under aerobic condition, NreB is dephosphorylated and its iron-sulfur cluster is destroyed (Figure 4). [From [START_REF] Kamps | Staphylococcal NreB: An O2-Sensing Histidine Protein Kinase with an O2-Labile Iron-Sulphur Cluster of the FNR Type[END_REF]].

Iron restriction

Metal ions are crucial elements for life processes including virulence. In bacteria, some metal ions like iron, magnesium and manganese are essential elements required for growth and play important roles in metalloproteins.

Iron (Fe) is mainly found in two common oxidation state, ferrous (Fe 2+ ) and ferric (Fe 3+ ). Ferrous irons are solube while ferric irons are insoluble and also the most stable form of iron. The difference in solubility of Fe 2+ and Fe 3+ leads to difficulties for bacteria to acquire iron. Therefore, bacteria not only develop mechanisms to uptake iron from the environment by solubilizing and assimilating it; but also have to compete for iron with other microorganisms or with the host. On the other hand, the quantity of intracellular iron has to be strictly controlled since an excess is toxic.

In S. aureus, there are three Ferric uptake repressors (Fur) homologues called Fur, PerR and Zur. When iron is present in bacteria, it binds to Fur. The Fe-Fur complex then binds to inverted repeat motifs called Fur boxes located in promoter regions of Furregulated genes. A Fur depletion in S. aureus generates a growth defect due to an excessive acquisition of iron and a decrease of the katA expression (Horsburgh, Ingham, and Foster 2001). There is a coupling between iron and oxidative regulations via the Fenton reaction.

When peroxide or superoxide reacts with iron, they form harmful hydroxyl radicals which are reduced by catalases or peroxidases. The murine abscess model was used to test the role of Fur in virulence; fur mutant had a reduced virulence compared to the wild-type strain. A proteomic study revealed that in iron-limiting conditions or after fur depletion, genes involved in glycolysis, iron acquisition and transport were upregulated while genes in the TCA cycle and rsbU were downregulated [START_REF] Friedman | Staphylococcus Aureus Redirects Central Metabolism to Increase Iron Availability[END_REF].

PerR is a second Fur homologue in S. aureus. PerR was shown to sense peroxide level inside the cell and control iron storage proteins (Horsburgh et al. 2001). The PerR-dependent regulon comprises not only oxidative stress resistance genes such as catalase (katA), alkyl hydroperoxide reductase (ahpCF) but also iron storage related genes such as ferritin (ftn), mgrA and fur. Like fur, the perR mutant had a reduced survival in murine abscess model infection (Horsburgh et al. 2001). PerR is also involved in the pathogenesis of Streptococcus pyogenes, Listeria monocytogenes and Enterococcus faecalis.

The third Fur-like protein in S. aureus is Zur. Its gene is within an operon encoding two putative membrane proteins with homology to zinc and other metal transporters [START_REF] Lindsay | Zur: A Zn2+-Responsive Regulatory Element of Staphylococcus Aureus[END_REF]. In S. aureus, the depletion of Zur did not affect Zn 2+ uptake but its overexpression was shown to affect the whole operon in a Zn 2+ -dependent manner. zur homologues were shown to regulate zinc uptake and ribosomal protein paralogs in B. subilis [START_REF] Panina | Comparative Genomics of Bacterial Zinc Regulons: Enhanced Ion Transport, Pathogenesis, and Rearrangement of Ribosomal Proteins[END_REF] and were involved in virulence in Salmonella enterica [START_REF] Campoy | Role of the High-Affinity Zinc Uptake znuABC System in Salmonella Enterica Serovar Typhimurium Virulence[END_REF] and Xanthomonas campestris [START_REF] Tang | The Zinc Uptake Regulator Zur Is Essential for the Full Virulence of Xanthomonas Campestris Pv. Campestris[END_REF]. In contrast, S. aureus zur did not play a role in pathogenicity in a mouse skin infection model [START_REF] Lindsay | Zur: A Zn2+-Responsive Regulatory Element of Staphylococcus Aureus[END_REF].

Temperature 1.3.1. Cold shock

In E. coli, CspA is a major cold shock protein [START_REF] Goldstein | Major Cold Shock Protein of Escherichia Coli[END_REF]). In S. aureus, cspA was found to positively regulate the yellow pigment 4,4'-diaponeurosporene [START_REF] Katzif | CspA Regulates Pigment Production in Staphylococcus Aureus through a SigB-Dependent Mechanism[END_REF]. Transcriptome and mRNA turnover rates in response to cold shock were studied by Affymetrix GeneChips (Anderson et al. 2006). The cspA gene was moderately induced (2fold) by a cold shock, while for two other cold shock genes, cspB was upregulated 9-fold and no change was observed for cspC expression. In addition, 46 genes upregulated and 416 genes downregulated by cold shock were identified. Many virulence factor genes [i.e. seo (enterotoxin), lip (lipase), srtA (sortase)], and regulatory genes [i.e. lexA (a SOS repressor)

and SACOL0958 (general stress protein)] were also induced in cold shock condition.

Surprisingly, cspC was strongly induced in oxidative stress (with hydrogen peroxide), salt condition by arsenate and various antibiotics such as ciprofloxacin, rifampicin, ampicillin, and cephalothin [START_REF] Chanda | Antibiotics, Arsenate and H2O2 Induce the Promoter of Staphylococcus Aureus cspC Gene More Strongly than Cold[END_REF]).

Heat shock

CtsR and HrcA, SarA and Sigma B are regulators involved in heat shock adaptation in S. aureus [START_REF] Clements | Characterization of the Major Superoxide Dismutase of Staphylococcus Aureus and Its Role in Starvation Survival , Stress Resistance , and Pathogenicity Characterization of the Major Superoxide Dismutase of Staphylococcus Aureus and Its Role in Starvation[END_REF].

HcrA is a repressor of class I heat shock genes encoding dnaK and the groESL operons. CtsR has a dual function: it is a repressor of class III heat shock genes (encoding Clp ATP-dependent proteases) but also works together with HcrA to repress chaperon protein genes [START_REF] Chastanet | Comparative Genomics Reveal Novel Heat Shock Regulatory Mechanisms in Staphylococcus Aureus and Other Gram-Positive Bacteria[END_REF]) (Figure 5). Sigma B ( B ) is a transcriptional factor that associates with RNA polymerase to initiate transcription. In S. aureus,  B is an alternative "stress" sigma factor that modulates many stress response genes. [Adapted from [START_REF] Chastanet | Comparative Genomics Reveal Novel Heat Shock Regulatory Mechanisms in Staphylococcus Aureus and Other Gram-Positive Bacteria[END_REF]].

Studies of the transcriptomic profile in response to heat shock revealed that 98 genes increased and 42 genes decreased (Anderson et al. 2006). Like for a cold shock, the viability of bacteria was not affected. The three heat shock genes, ctsR, clpB and clpC were significantly increased. In addition, many putative virulence genes [i.e. hla (-hemolysin), pathogenicity island genes, urea-ureG (urease system)] were upregulated. Interestingly, 11 genes were induced in both heat and cold shock conditions; they may belong to the same family of temperature-mediated response genes.

pH

Electron transport chain is the last process of aerobic respiration to generate the energy. The main function of this chain is transferring electrons from donors to acceptors and associated with proton pumps that transfer protons (hydrogen ions) across a membrane to create an electrochemical proton gradient that powers ATP production. pH or the hydrogen ion concentration is the main factor affecting the cytoplasmic pH homeostasis of bacteria. Therefore, to maintain the growth, bacteria need to develop pH sensing and mechanisms to keep balance their cytoplasmic pH homeostasis.

Acid shock

Many bacteria, including pathogens, need to adapt to acidic conditions, i.e. in dairy food like yogurts, fermented milk or inside the gastrointestinal system. For example, the Gram-positive pathogen L. monocytogenes survives in the human stomach and even inside the phagosome. The ability to tolerate acidic pH is considered as a virulence factor for bacteria.

There are 8 known mechanisms for acid resistance in Gram-positive bacteria (Figure 6). They can maintain their intracellular pH either by proton pumps (GAD system, F1F0ATPase) that increase the uptake of hydrogen ion or by generating alkaline products such as NH 3 / NH 4 + (via an arginine deiminase (ADI) pathway) and an urease system that counteracts acid pH. Other mechanisms are protein and DNA repair systems. Some genes involved are dnaK, groEL, htr, clp ATPases and lo18 for protein repair systems and recA, uvr and smn for DNA repair systems.

During an acidic challenge, bacteria alter their general energy and metabolism, and cell envelope, a switch that is needed for the adaptation. The role of the cell membrane is demonstrated by changes in membrane fatty acid profiles [START_REF] Cotter | Surviving the Acid Test : Responses of Gram-Positive Bacteria to Low pH Surviving the Acid Test : Responses of Gram-Positive Bacteria to Low pH[END_REF]. A

Streptococcus mutants strain with a dltC (encoding the D-alanyl carrier protein, Dcp) deletion was more sensitive to acid with a longer doubling-time and reduced growth yield than the parental strain [START_REF] Boyd | Defects in D-Alanyl-Lipoteichoic Acid Synthesis in Streptococcus Mutans Results in Acid Sensitivity[END_REF]. The inactivation of dltC prevents the D-alanylation of lipoteichoic acids (LTAs), a main cell wall compound in Gram-positive bacteria.

Bacteria also resist to media acidification via global regulators such as TCSs and sigma factors. For example, in L. monocytogenes the depletion of lisRK encoding a TCS generates an altered acid shock response. The lisRK mutant was more sensitive to long time exposure to acid in stationary phase while it was more resistant to short time exposure during prestationary phase compared to the wild-type strain [START_REF] Cotter | Identification and Disruption of lisRK , a Genetic Locus Encoding a Two-Component Signal Transduction System Involved in Stress Tolerance and Virulence in Listeria Monocytogenes Identification and Disruption of lisRK , a Genetic Locus Encoding a Two-Compo[END_REF]. The  B mutant is more sensitive to acid stress with a rapid loss of viability. S. aureus can be killed by a pH 2 but its resistance to acid increases if it is first pre-incubated at pH4, a non-lethal condition [START_REF] Chan | The Staphylococcus Aureus Alternative Sigma Factor sigmaB Controls the Environmental Stress Response but Not Starvation Survival or Pathogenicity in a Mouse Abscess Model[END_REF]). In addition, the sodA (encoding a major superoxide dismutase) mutant has a reduced viability at low pH as compared to the wild-type strain [START_REF] Clements | Characterization of the Major Superoxide Dismutase of Staphylococcus Aureus and Its Role in Starvation Survival , Stress Resistance , and Pathogenicity Characterization of the Major Superoxide Dismutase of Staphylococcus Aureus and Its Role in Starvation[END_REF]. These results demonstrated the role of  B and SodA to adapt to acid stress. However, the mechanism of sodA involved in acid resistance is still not clear.

Several studies were performed to determine the gene expression under different acidic conditions, such as growth in mild acidic condition (pH5.5) [START_REF] Weinrick | Effect of Mild Acid on Gene Expression in Staphylococcus Aureus[END_REF]; acid shock at pH 4.5 during 20 min [START_REF] Bore | Acid-Shock Responses in Staphylococcus Aureus Investigated by Global Gene Expression Analysis[END_REF], acid shock at pH 4 during 30 min [START_REF] Anderson | Characterizing the Effects of Inorganic Acid and Alkaline Shock on the Staphylococcus Aureus Transcriptome and Messenger RNA Turnover[END_REF]). The results from Anderson et al not only confirmed many genes and overlapped with previous studies but also extended the network of genes related to acid stress adaptation. Interestingly, a total of 15 virulence genes were found downregulated in acidic condition including 7 known genes involved in acidic adaptation from [START_REF] Bore | Acid-Shock Responses in Staphylococcus Aureus Investigated by Global Gene Expression Analysis[END_REF]. Five new additional virulence factors i.e. spa, chemotaxis-inhibiting protein CHIPS (chp), clumping factor B (clfB), fibrinogen-binding protein (efb) and staphylokinase precursor (sak) were revealed in this study. Moreover, 4 TCS such as SaeRS, LytSR, ArlSR and GdpS were also observed to be downregulated in response in acidic condition.

S. aureus is also a major cause of food poisoning. During food conservation, it undegoes stress associated with organic acids like lactic and acetic acids. S. aureus responses to medium containing these acids was explored by microarrays [START_REF] Rode | Responses of Staphylococcus Aureus Exposed to HCl and Organic Acid Stress[END_REF]. First, a large variation in growth patterns was observed: bacterial growth was inhibited in medium containing acetic acid whereas bacteria exposed to lactic acid had a longer lag phase than when growing in medium containing HCl. Interestingly, only the pH of the culture containing lactic acid increased up to pH 7.5 during growth. Thus, compared with HCl induction, the response to lactic acid stress induced a specific mechanism to increase pH by accumulating ammonium and removing acid groups with production of diacetyl (2,3-butane dione) and pyrazines .

Alkaline shock

The first study on alkaline effect in S. aureus was reported in 1992 [START_REF] Regassa | Alkaline pH Decreases Expression of the Accessory Gene Regulator (agr) in Staphylococcus Aureus[END_REF]. The expression of the agr (accessory gene regulator) quorum sensing system (see chapter IV) examined in alkaline condition (pH from 6.5 to 8) revealed that the expression of RNAIII, one of the transcripts of agr locus, was higher at pH 7 but mostly vanished at pH 8.

The expression of sec (staphylococcal enterotoxin type C), a target of the agr system, was also reduced in alkaline stress. Alkaline stress was found to strongly induce  B transcription and 122  B -dependent genes (involved in capsule biosynthesis, Na+/H+ antiporter system and autolysin) were upregulated during this stress [START_REF] Pané-Farré | The σB Regulon in Staphylococcus Aureus and Its Regulation[END_REF].

A microarray assay was also performed in alkaline condition (pH10 during 30 min) [START_REF] Anderson | Characterizing the Effects of Inorganic Acid and Alkaline Shock on the Staphylococcus Aureus Transcriptome and Messenger RNA Turnover[END_REF]. Cell viability in alkaline stress was not affected, but 128 transcripts increased while 773 transcripts decreased. Downregulated genes were involved in nucleotide biosynthesis, amino acid metabolism and translation while upregulated were involved in amino acid biosynthesis (lysine, valine, isoleucine, histidine and threonine) and virulence (capsule biosynthesis). Interestingly, the alkaline shock stimulon induces the expression of (p)ppGpp, the activator of the stringent response.

Host-pathogen interaction

S. aureus is a versatile human pathogen, hence this bacterium needs to develop efficient mechanisms to survive in host defense and resist to the host immune system.

Briefly, the human immune system comprises a non-specific (innate) and specific (adaptive or acquired) immunity systems (Figure 7). The non-specific system includes two lines of defense. The first line consists of physical and chemical barriers, natural flora and mechanical barriers. If bacteria can pass the first line, they will face the second line of defense that includes defensive molecules, phagocytosis, complement and protective mechanisms. The specific immune system involves lymphocytes and antibodies which will recognize and eliminate pathogens, their toxins products, and also confers long-term protection by developing immunological memories.

III. Overview of bacterial competitive fitness

The fitness of a bacterial strain could be explained from a Darwinian point of view.

From his theory, "survival of the fittest" is the main concept of natural selection that is mechanism by which species adapt and evolve. It could be defined as an increase of frequency or its probability of survival in competition with others. The individuals having variants that best fit to the environment (fittest) have better potential for survival, reproduction and passing their desirable variations to their offsprings.

Based on this concept, one way to define the bacterial fitness in the laboratory conditions is a competitive fitness assay by growing two or more strains together that allow them to compete and evaluate their ratio at different times (Figure 9). In addition, growth in the presence of other strains reflects a more "real" situation, as the fitness of one strain may be affected by the genetically different surrounding strains. Therefore, these experiments could reveal patterns of interaction or epistasis among different strains and possibly whether particular combinations of strains interact synergistically or antagonistically [START_REF] Zhan | Experimental Measures of Pathogen Competition and Relative Fitness[END_REF]. Interestingly, variants leading to improved fitness in one growth condition can lead to altered fitness in another condition, as the result is often a compromise [START_REF] Mariam | Effect of rpoB Mutations Conferring Rifampin Resistance on Fitness of Mycobacterium Tuberculosis[END_REF]) (MacLean & Vogwill 2014).

Figure 9: Scheme of a competitive fitness assay. The strain to be assayed is mixed with a reference strain, and the ratio of the two is measured before and after growth. [From [START_REF] Desai | Statistical Questions in Experimental Evolution[END_REF]].

The classical way to carry out fitness assays is to label the strains with different antibiotic resistance or fluorescent markers. However, one impediment is the limited number of available markers; hence fitness assays are difficult to perform on a large scale.

As a result, one possibility to easily follow many strains in the same culture is to introduce specific DNA sequences for each constructed strains. These sequences, called DNA barcodes, can then be quantitatively detected within a mix culture. A DNA barcode acts as a specific "marker" that represents the relative presence of a strain in the population.

The first application of DNA barcodes was in Salmonella typhimurium to identify genes involved in pathogenesis using a murine model of typhoid fever [START_REF] Hensel | Simultaneous Identification of Bacterial Virulence Genes by Negative Selection[END_REF].

Briefly, the DNA barcodes contained 40 random nucleotides flanked by common priming regions on each side. The DNA barcodes were ligated with transposons and used to mutagenize S. typhimurium genome. A bank of 1152 transposon-tagged mutants was obtained and arrayed in twelve 96-well microtiter plates. DNA colony blots were made from microtiter dishes by replica plating them on a membrane. The mutants of each microtiter plate were pooled together and used to infect mice. After 3 days of infection, spleens were recovered, homogenized and plated to recover the infecting mutants. Approximately 10,000 obtained colonies were pooled together. Chromosomal DNAs were extracted and DNA barcodes were amplified (using conserved priming regions for all tags), radiolabeled and hybridized with DNA colony blots (Figure 4). Virulence genes were found by identifying DNA barcodes that were present in the control samples but not in the infected ones. These DNA barcodes corresponded to insertions leading to attenuated virulence (Figure 10). pool that is used to infect the mice. [From (Mazurkiewicz et al. 2006)].

This technique was subsequently developed in yeast (Shoemaker et al. 1996;[START_REF] Pierce | Genome-Wide Analysis of Barcoded Saccharomyces Cerevisiae Gene-Deletion Mutants in Pooled Cultures[END_REF][START_REF] Smith | Quantitative Phenotyping via Deep Barcode Sequencing[END_REF][START_REF] Han | Global Fitness Profiling of Fission Yeast Deletion Strains by Barcode Sequencing[END_REF][START_REF] Chen | Generation and Analysis of a Barcode-Tagged Insertion Mutant Library in the Fission Yeast Schizosaccharomyces Pombe[END_REF]), and used with other bacteria [START_REF] Rooney | A Molecular Bar-Coded DNA Repair Resource for Pooled Toxicogenomic Screens[END_REF]Hobbs et al. 2010).

In many published fitness protocols, tags were analyzed by hybridizing labeled PCR products on dedicated DNA arrays [START_REF] Hensel | Simultaneous Identification of Bacterial Virulence Genes by Negative Selection[END_REF]Shoemaker et al. 1996;[START_REF] Pierce | Genome-Wide Analysis of Barcoded Saccharomyces Cerevisiae Gene-Deletion Mutants in Pooled Cultures[END_REF][START_REF] Rooney | A Molecular Bar-Coded DNA Repair Resource for Pooled Toxicogenomic Screens[END_REF]Hobbs et al. 2010). These experiments are rather heavy and expensive as each tested condition required at least one array. The protocol was adapted to deep sequencing technology to improve its sensitivity and its ease-of-use [START_REF] Smith | Quantitative Phenotyping via Deep Barcode Sequencing[END_REF][START_REF] Han | Global Fitness Profiling of Fission Yeast Deletion Strains by Barcode Sequencing[END_REF]) (chapter A).

IV. Overview of regulatory RNAs in S. aureus

Besides the central roles of mRNA, rRNA and tRNA in translation, the regulatory role of RNAs in prokaryote gene expression is nowadays well established. They can act either in trans, targeting RNAs and proteins, or in cis by affecting adjacent or associated sequences.

Through sophisticated mechanisms, these regulatory RNAs fine-tune genetic expression to allow bacterial fitness and adaptation to varied environments including those within their dedicated hosts. They usually exert their functions at the levels of transcription and/or translation of their mRNA targets (Storz et al. 2011;[START_REF] Guillet | Emerging Functions for the Staphylococcus Aureus RNome[END_REF]).

Identification of regulatory RNAs by various approaches

The first regulatory RNAs in S. aureus was discovered in 1993 and named RNAIII (see chapter IV.3 for more details). Later, several studies contributed to identify numerous S.

aureus regulatory RNAs based on computational prediction (Geissmann et al. 2009;Marchais et al. 2009;[START_REF] Pichon | Small RNA Genes Expressed from Staphylococcus Aureus Genomic and Pathogenicity Islands with Specific Expression among Pathogenic Strains[END_REF], Affymetrix microarrays [START_REF] Anderson | Characterizing the Effects of Inorganic Acid and Alkaline Shock on the Staphylococcus Aureus Transcriptome and Messenger RNA Turnover[END_REF]Roberts et al. 2006;Anderson et al. 2006), sequence cDNA libraries (Abu-Qatouseh et al. 2010) and high throughput sequencing (Bohn et al. 2010;[START_REF] Beaume | Cartography of Methicillin-Resistant S. Aureus Transcripts: Detection, Orientation and Temporal Expression during Growth Phase and Stress Conditions[END_REF]Lasa et al. 2011;Lioliou et al. 2012;[START_REF] Howden | Analysis of the Small RNA Transcriptional Response in Multidrug-Resistant Staphylococcus Aureus after Antimicrobial Exposure[END_REF]. Several targets from these identified sRNAs were experimentally validated (see Table 1). So far, the transcription of approximately 250 staphylococcal regulatory RNAs was experimentally confirmed [review from (Felden et al. 2011)]. [START_REF] Roberts | Characterizing the Effect of the Staphylococcus Aureus Virulence Factor Regulator, SarA, on Log-Phase mRNA Half-Lives[END_REF]). e A number of different names have been assigned to many of these sRNAs. In this table, the initial name from the relevant study has been used. A full list of alternate names can be found in the supplementary table from (Felden et al. 2011). Recently, a uniform nomenclature for S. aureus regulatory RNAs was proposed [START_REF] Sassi | SRD : A Staphylococcus Regulatory RNA Database[END_REF].

(srn_3340), Teg73 (srn_3490, RsaOE, sRNA276), Teg76 (srn_0930, sRNA74), Teg91 (srn_1640, rsaD, sRNA138), Teg2pl

Classification

Regulatory RNAs exert usually their activity by base-pairing with target mRNAs or by binding to proteins. Some regulatory RNAs have a cis-regulatory activity on associated RNA sequences. Most regulatory RNAs are active under specific conditions and influence gene expression in response to environmental changes. They can bind mRNA ribosome-binding site (RBS), inhibit and stimulate translation or RNA degradation. According to their predicted mode of action, regulatory RNAs can be categorized as follows.

2.1 Regulatory small RNAs targeting mRNAs

Cis-encoded antisense RNAs

Cis-encoded antisense RNAs (asRNAs) are expressed from DNA strands opposite to genes. The predicted putative target of asRNAs is the mRNA expressed from the opposite strand. asRNAs share extended regions of complete complementarity with their target The first asRNA reported in S. aureus was RNAI from plasmid pT181 [START_REF] Novick | pT181 Plasmid Replication Is Regulated by a Countertranscript-Driven Transcriptional Attenuator[END_REF]. RNAI associates by base-pairing with repC mRNA and consequently inhibits the expression of RepC, a replication initiation protein. A second asRNA, RNAII, transcribed from the same promoter as RNAI, but longer than RNAI is also involved in pT181 replication as show on figure 12. RepC synthesis is thus prevented. [From [START_REF] Romilly | Current Knowledge on Regulatory RNAs and Their Machineries in Staphylococcus Aureus[END_REF]].

RsaOW is an example of an asRNA expressed from mobile elements, which pairs with the 5'UTR of the transposase gene of IS1181. RsaOW has eight copies from rsaOW1 to rsaOW8 in N315 genome and is expressed constitutively likely to block expression of the IS1181 transposase (Bohn et al. 2010).

asRNAs were also reported from S. aureus core genome. The first high-throughput sequencing of N315 transcriptome revealed that at least 1.3% of mRNAs were covered by asRNAs [START_REF] Beaume | Cartography of Methicillin-Resistant S. Aureus Transcripts: Detection, Orientation and Temporal Expression during Growth Phase and Stress Conditions[END_REF]). However, this percentage is likely much higher. In this recent study, long (>75 nt) and short (<50 nt) transcripts of strain NCTC8325 were analyzed by RNA deep sequencing. The authors concluded that 49% of the ORFs are covered on at least 50% of their length by long asRNAs and up to 75% of ORF in case of short transcripts (Lasa et al. 2011).

Trans-encoded RNAs (sRNAs)

In contrast to cis-encoded asRNAs, trans-encoded RNAs (often referred to as sRNAs), are expressed from DNA regions with no RNA expressed on their opposite strand. sRNAs are usually small, typically between 50 and 500 nucleotides in length, and non-coding (Gottesman and Storz 2011). Their RNA targets are usually located at different positions on the chromosome. Hence, the base pairing length between a sRNA and its target is often limited, typically about 10-25 nucleotides [START_REF] Waters | Regulatory RNAs in Bacteria[END_REF]. Their mode of action is quite depicted in figure 13. In S. aureus, the sRNA/RNA interaction seems to require a longer pairing than in many other organisms, possibly because S. aureus has a low GC content genome therefore generating weaker RNA-RNA interactions. Most of sRNAs have a conserved "seed" motif UCCC to initiate the pairing with RNA targets (Figure 14) (Geissmann et al. 2009).

A B

Cis-regulatory elements

In bacteria, cis-regulatory RNAs may be located in the 5' or 3' untranslated regions (UTR) of mRNA and hence act in cis. Under specific condition, cis-regulatory RNAs can sense environmental signals such as metabolites (riboswitches), uncharged tRNAs (T-boxes), metal ions, pH and temperature (thermoswitches) and then adopt different conformations thus regulating the expression of downstream genes.

The most widespread examples of cis-regulatory sRNAs in bacteria are riboswitches that play a major role in regulating genes involved in metabolic pathways. Riboswitches sense metabolites such as cofactors, vitamins, amino acids, nucleotides, the second messenger cyclic di-GMP, metal ions. Generally, riboswitches are composed of two parts: i) the aptamer region which binds ligands (metabolites) and ii) the expression platform which changes its structure in response to the ligand binding. mRNA modifications usually involve alternative hairpin structures creating transcription terminators and antiterminators or structures occluding and exposing RBSs, thus controlling translation. In most cases, the presence of ligands inhibit transcription or translation (Figure 15). Many S. aureus riboswitches were discovered by biocomputing analysis of genome sequences to identify conserved metabolite-binding domains (Barrick & Breaker 2007) [START_REF] Yao | A Computational Pipeline for High-Throughput Discovery of Cis-Regulatory Noncoding RNA in Prokaryotes[END_REF]); among them riboswitches sensing S-adenosylmethionine (SAM), thiamine pyrophosphate (TPP), flavin mononucleotide (FMN), lysine, glycine, guanine, 7-aminomethyl-7-deazaguanine (preQ1) and glucosamine-6-phosphate (Glc-6P) (Geissmann et al. 2009;Marchais et al. 2009;Abu-Qatouseh et al. 2010;[START_REF] Beaume | Cartography of Methicillin-Resistant S. Aureus Transcripts: Detection, Orientation and Temporal Expression during Growth Phase and Stress Conditions[END_REF]Bohn et al. 2010;[START_REF] Broeke-Smits | Operon Structure of Staphylococcus Aureus[END_REF].

Antibiotic binding to riboswitches can be used to develop new treatments for multiple drug resistant strains. Some riboswitches are known as antimicrobial targets such as TPP, lysine, FMN and guanine riboswitches [review in [START_REF] Mulhbacher | Therapeutic Applications of Ribozymes and Riboswitches[END_REF]].

Recently, novel putative ligands that can bind to guanine riboswitches were selected based on a model of the crystal structures. Two pyrimidine-based molecules named pyrimidine compound 1 (PC1) and pyrimidine compound 2 (PC2) were identified. PC1 showed antibacterial activity in vitro against S. aureus and Clostridium difficile. PC1 was also tested in a mouse model and shown to decrease S. aureus growth in the mammary gland [START_REF] Mulhbacher | Novel Riboswitch Ligand Analogs as Selective Inhibitors of Guanine-Related Metabolic Pathways[END_REF].

Another example of riboswitch is associated with the tightly control of the methionine biosynthesis operon in S. aureus. This regulation is a complex combination of the action of stringent-mediated repressor CodY, T-box riboswitch and methionine metlCFE-mdh operon as explained in figure 16 [START_REF] Schoenfelder | Methionine Biosynthesis in Staphylococcus Aureus Is Tightly Controlled by a Hierarchical Network Involving an Initiator tRNA-Specific T-Box Riboswitch[END_REF]. uncharged tRNA i fMet levels and determines transcription of the met biosynthesis genes in a highly methioninedependent manner. Rapid degradation of the met mRNA by the RNA degradosome is an additional mechanism to limit unnecessary translation of methionine biosynthesis mRNA. [From [START_REF] Schoenfelder | Methionine Biosynthesis in Staphylococcus Aureus Is Tightly Controlled by a Hierarchical Network Involving an Initiator tRNA-Specific T-Box Riboswitch[END_REF]].

Many cis-regulatory elements are present in S. aureus; however, so far, most of them are not characterized.

Protein-targeting RNAs

Protein-targeting RNAs are regulatory RNAs that directly interact with proteins to modulate their activity. Some of these proteins belong to ribonucleoprotein complexes and [START_REF] Pichon | Small RNA Genes Expressed from Staphylococcus Aureus Genomic and Pathogenicity Islands with Specific Expression among Pathogenic Strains[END_REF]. However, this bacterium does not have the CsrB/CsrA and GlmY/YhbJ systems.

6S sRNA is a global regulator conserved in bacteria [START_REF] Barrick | 6S RNA Is a Widespread Regulator of Eubacterial RNA Polymerase That Resembles an Open Promoter[END_REF][START_REF] Trotochaud | A Highly Conserved 6S RNA Structure Is Required for Regulation of Transcription[END_REF]. In E.coli, 6S sRNA sequestrates  70 -core RNA polymerase by mimicking a promoter sequence (Figure 17). This interaction represses the expression of many  70dependent transcription in stationary phase due to the abundance of 6S in this phase [START_REF] Wassarman | 6S RNA Regulates E. Coli RNA Polymerase Activity[END_REF]. Moreover, 6S sRNA also upregulates the general stress σ Sdependent transcription in vivo [START_REF] Trotochaud | A Highly Conserved 6S RNA Structure Is Required for Regulation of Transcription[END_REF][START_REF] Cavanagh | 6S RNA, A Global Regulator of Transcription in Escherichia Coli, Bacillus Subtilis, and Beyond[END_REF]. 6S sRNA was found to be highly expressed in stationary phase of four S. aureus pathogenic strains [START_REF] Pichon | Small RNA Genes Expressed from Staphylococcus Aureus Genomic and Pathogenicity Islands with Specific Expression among Pathogenic Strains[END_REF]. However, there is no homolog of σ S in S. aureus.

Instead, σ B is the general stress sigma factor involved in environmental response and virulence factor expression [START_REF] Gertz | Characterization of the sigma(B) Regulon in Staphylococcus Aureus[END_REF]. Therefore, staphylococcal 6S RNA is possibly associated with different regulations than in E. coli.

Role of regulatory RNAs in S. aureus

Regulatory RNAs play multiple roles in S. aureus. Their expression was observed in several stress conditions including starvation, antibiotic treatment and host infection (Anderson et al. 2006;Geissmann et al. 2009;[START_REF] Beaume | Cartography of Methicillin-Resistant S. Aureus Transcripts: Detection, Orientation and Temporal Expression during Growth Phase and Stress Conditions[END_REF]Bohn et al. 2010;[START_REF] Anderson | Characterizing the Effects of Inorganic Acid and Alkaline Shock on the Staphylococcus Aureus Transcriptome and Messenger RNA Turnover[END_REF][START_REF] Howden | Analysis of the Small RNA Transcriptional Response in Multidrug-Resistant Staphylococcus Aureus after Antimicrobial Exposure[END_REF]. Several examples of S. aureus regulatory RNAs involved in metabolism, stress response, environmental adaptation and virulence will be presented below.

RNAIII is the most well-known Staphylococcal sRNA. It is the intracellular effector of the agr system (Novick et al. 1993) that controls the expression of many virulence genes by a two-component signaling module. The agr locus encodes a quorum sensing system (agrBDCA) and RNAIII driven by the P2 and P3 promoters, respectively (Figure 18). AgrD encodes an autoinducing peptide (AIP) while AgrB is a transmembrane protein that processes and secretes this peptide. At the high cell densities, the secreted AIP molecules accumulate and reach a threshold level that can bind and activate the receptor histidine kinase AgrC. Then, the phosphorylated AgrC can activate the sensor regulator AgrA by transferring its phosphate group. As a consequence, the phosphorylated AgrA binds to the P2 and P3 promoters to induce RNAII and RNAIII transcripts. Therefore, RNAIII accumulates and its maximal expression is in late-exponential and stationary growth phases. RNAIII regulates important processes such as biofilm formation, peptidoglycan and amino acid metabolism, and transport pathways (Novick and Geisinger 2008). RNAIII upregulates genes involved in toxin secretion and enzyme production whereas it affects many downstream genes that encode cell wall-associated proteins. Thus, RNAIII plays a role in the switch of gene expression occurring when S. aureus reaches stationary phase. RNAIII is a unique example of one RNA molecule containing activities such as mRNA, an activator RNA, and an inhibitory RNA (Figure 19): i) RNAIII is a messenger RNA containing a small ORF encoding the-hemolysin. ii) the secondary structure near the 5' end of RNAIII acts as an antisense RNA. It base-pairs to a 5' segment of hla (hemolysin α) mRNA and sequesters the anti-Shine and Dalgarno sequence thus activating hla translation. iii) RNAIII directly basepairs with rot (repressor of toxins), spa (protein A), lytM (autolysin) and sbi mRNA and represses their translations (Novick et al. 1993;[START_REF] Geisinger | Inhibition of Rot Translation by RNAIII, a Key Feature of Agr Function[END_REF][START_REF] Chunhua | The Expression of LytM Is down-Regulated by RNAIII in Staphylococcus Aureus[END_REF]Chabelskaya et al. 2014). In addition, RNAIII also was shown to negatively regulate the transcriptional regulator sarT mRNA (Boisset et al. 2007).

In addition to RNAIII, a second sRNA named ArtR (AgrA-repressed, toxin-regulating sRNA) is regulated by the agr system [START_REF] Xue | ArtR, a Novel sRNA of Staphylococcus Aureus, Regulates Alpha-Toxin Expression by Targeting the 5' UTR of sarT mRNA[END_REF]. ArtR directly binds to sarT mRNA (encoding a repressor of α-hemolysin) and promotes the duplex degradation by RNase III.

Through SarT, ArtR indirectly activates hla expression (Figure 19).

The psm-mec RNA transcribed from the SCCmec mobile element (which contributes to S. aureus antibiotic methicillin resistance) is another example of sRNA with a dualfunction. First, psm-mec contains a small ORF that encodes a 22 amino-acid cytolysin, phenol-soluble modulin (PSMα). Second, psm-mec RNA inhibits translation of agrA through direct interaction, leading to decreased extracellular toxin production, hence reduce virulence [START_REF] Kaito | Mobile Genetic Element SCCmec-Encoded Psm-Mec RNA Suppresses Translation of agrA and Attenuates MRSA Virulence[END_REF].

Other known sRNAs important for virulence of S. aureus are SprA1 AS , SSR42 and Teg49. Firstly, SprA1 AS is an antisense of SprA1, a sRNA encoding a human cytolytic peptide.

Surprisingly, the pairing region between SprA1 AS and SprA1 is not in the 35-nucleotide perfectly complementary region. Instead, SprA1 AS asRNA interacts with the 5'end of SprA1 to sequester the SprA1 SD sequence and prevents translation initiation [START_REF] Sayed | A Cis -Antisense RNA Acts in Trans in Staphylococcus Aureus to Control Translation of a Human Cytolytic Peptide[END_REF].

Secondly, SSR42 is a 891-nucleotide long RNA that belongs to the small stable RNAs (SSRs) group. SSR42 is induced in stationary phase and controls a large number of genes including virulence ones; it is required for pathogenicity in a murine model of S. aureus skin and soft tissue infection [START_REF] Morrison | Characterization of SSR42, a Novel Virulence Factor Regulatory RNA That Contributes to the Pathogenesis of a Staphylococcus Aureus USA300 Representative[END_REF]. Thirdly, Teg49 RNA is located upstream of sarA, which encodes a transcriptional regulator. Teg49 was shown to modulate sarA expression which is involved in S. aureus pathogenicity [START_REF] Kim | Contribution of teg49 sRNA in the 5'-Upstream Transcriptional Region of sarA to 2 Virulence in Staphylococcus Aureus[END_REF]. One interesting example is RsaE, a 93-nt long unique sRNA conserved in Staphylococcus, Macrococcus and Bacillus genera (Geissmann et al. 2009;Bohn et al. 2010).

The transcription of RsaE is strongly enhanced in stationary phase in strain RN6390 (Geissmann et al. 2009) but in many clinical strains, RsaE accumulates in pre-stationary phase and is repressed in stationary phase (Bohn et al. 2010;[START_REF] Song | The Expression of Small Regulatory RNAs in Clinical Samples Reflects the Different Life Styles of Staphylococcus Aureus in Colonization vs. Infection[END_REF]. The rsaE transcription is up-regulated by the agr system and down-regulated in  B+ strain (Geissmann et al. 2009).

RsaE plays an important role in S. aureus metabolism (Figure 20). It downregulates various enzymes involved in the Krebs cycle and the folate metabolic pathway. Specifically, RsaE directly represses the expression of two enzymes of the TCA cycle (SucC/SucD) and two oligopeptide transporters (Opp3A/B) by pairing to SD sequences of the targeted mRNAs hence preventing translation initiation (Geissmann et al. 2009;Bohn et al. 2010). In addition, RsaE upregulates genes encoding membrane proteins (opp4A/opp4D) and several operons such as valine, leucine and isoleucine biosynthetic operons.

So far no phenotype has been associated with the rsaE deletion in S. aureus (Geissmann et al. 2009;Bohn et al. 2010). Recently it was reported the rsaE orthologue gene in B. subtilis was induced by nitric oxide [START_REF] Durand | A Nitric Oxide Regulated Small RNA Controls Expression of Genes Involved in Redox Homeostasis in Bacillus Subtilis[END_REF]. Many genes involved in the oxidative stress response were upregulated in the rsaE mutant as compared to the wild-type strain. Thus, the rsaE gene was renamed roxS (Related to oxidative stress). RoxS was shown to affect the ppnKB mRNA (encoding an NAD+/NADH kinase) stability but also to prevent its translation.

Due to the interplay between RsaE, agr system and  B , it was suggested that RsaE could be an example of sRNA at the crossroad between metabolism and virulence [START_REF] Tomasini | The Importance of Regulatory RNAs in Staphylococcus Aureus[END_REF]. Another sRNA in S. aureus revealing links between adaptation and virulence is RsaA.

It is a typical  B -dependent sRNA, hence strongly expressed in  B+ strains (COL and Newman strains) (Geissmann et al. 2009). RsaA is also induced in small colony variants (SCV), a slowgrowing subpopulation in S. aureus (Abu-Qatouseh et al. 2010). Moreover, RsaA was found to be expressed in all S. aureus clinical isolates [START_REF] Romilly | A Non-Coding RNA Promotes Bacterial Persistence and Decreases Virulence by Regulating a Regulator in Staphylococcus Aureus[END_REF].

Recently, the global transcriptional regulator MgrA involved in biofilm formation and capsule synthesis was found to be negatively regulated by RsaA [START_REF] Romilly | A Non-Coding RNA Promotes Bacterial Persistence and Decreases Virulence by Regulating a Regulator in Staphylococcus Aureus[END_REF] In addition, the expression of SpoVG (a predicted target of RsaA by computational approach) involved in capsule synthesis was significantly increased in a rsaA mutant [START_REF] Romilly | A Non-Coding RNA Promotes Bacterial Persistence and Decreases Virulence by Regulating a Regulator in Staphylococcus Aureus[END_REF]. Importantly, RsaA was shown to affect S. aureus virulence in two mouse infection models by reducing bacterial invasiveness and enhancing local colonization. RsaA is the first characterized conserved sRNA in S. aureus that diminishes the severity of acute infection and favors chronic infection [START_REF] Romilly | A Non-Coding RNA Promotes Bacterial Persistence and Decreases Virulence by Regulating a Regulator in Staphylococcus Aureus[END_REF]. Several regulatory RNAs expressed from genomic pathogenicity islands (containing virulence and antibiotic resistance genes) in S. aureus were named Spr for "Small pathogenicity island RNAs" [START_REF] Pichon | Small RNA Genes Expressed from Staphylococcus Aureus Genomic and Pathogenicity Islands with Specific Expression among Pathogenic Strains[END_REF]. One of them expressed from the Pathogenicity Island  (PI), SprD, contributes significantly to disease in a mouse infection model. It prevents the translation initiation of the sbi mRNA (encoding immune evasion protein). SprD base-pairs with the sbi mRNA 5'-end to prevent ribosome loading by occluding the SD sequence and the initiation codon (Chabelskaya et al., 2010) (Figure 22). Sbi is also repressed by RNAIII by a similar mechanism (Chabelskaya et al. 2014) (see also chapter III.3.1). The regulation of sbi specifically depends on the expression of these 2 sRNAs which are expressed in exponential phase and stationary phase for SprD and RNAIII, respectively.

Figure 22: Base-pair association of SprD with sbi mRNA. SprD recognizes its target mRNA via a "loopsingle strand" interaction (green) that extends further upstream and downstream. [From (Chabelskaya et al., 2010)]. The hfq gene is present, so far, in all sequences of staphylococcal strains and the Hfq crystal structure of S. aureus (Hfq Sa ) was the first obtained [START_REF] Schumacher | Structures of the Pleiotropic Translational Regulator Hfq and an Hfq-RNA Complex: A Bacterial Sm-like Protein[END_REF].

Proteins involved in

Unexpectedly, the deletion of hfq Sa in strain RN6390 did not generate any detectable phenotype in  2000 tested growth conditions [START_REF] Bohn | No Detectable Effect of RNA-Binding Protein Hfq Absence in Staphylococcus Aureus[END_REF]). On the other hand, an hfq deletion in S. aureus NCTC8325-4 was shown to increase carotenoid pigments and to confer higher resistance to oxidative stress and reduced virulence [START_REF] Liu | Hfq Is a Global Regulator That Controls the Pathogenicity of Staphylococcus Aureus[END_REF]). These apparently contradictory results can be explained by a different expression of hfq between strains. hfq Sa is detected in NCTC8325-4 but not in RN6390 [START_REF] Liu | Hfq Is a Global Regulator That Controls the Pathogenicity of Staphylococcus Aureus[END_REF]. Intriguingly, in contrast to Liu et al results, hfq Sa mutants in several backgrounds including NCTC8325-4 constructed in our laboratory did not stimulate the production of S. aureus pigmentation (Chantal Bohn, unpublished results and figure 23). Surprisingly, Hfq Sa was not required for any sRNA activities tested, including interactions of the well-known regulatory RNA RNAIII with its targets [START_REF] Geisinger | Inhibition of Rot Translation by RNAIII, a Key Feature of Agr Function[END_REF]Boisset et al. 2007;Geissmann et al. 2009;Chabelskaya et al. 2010).

In S. aureus, long duplex pairings and formation of two-part binding sites between sRNAs and their mRNA targets are observed (e.g., RNAIII-rot mRNA, SprD-sbi mRNA or RsaA-mgrA mRNA) (Figure 24 and Chapter IV.3). In addition, S. aureus sRNAs have often C-rich motifs within loops involved in pairing interactions [ (Geissmann et al. 2009) and Chapter IV)].

Therefore, Hfq Sa may be dispensable because of these features [START_REF] Tomasini | The Importance of Regulatory RNAs in Staphylococcus Aureus[END_REF]). In addition, Hfq Sa contains a KANQ motif instead of an arginine rich motif RRER which is required for Hfq chaperone activity in E. coli [START_REF] Panja | Conserved Arginines on the Rim of Hfq Catalyze Base Pair Formation and Exchange[END_REF]; this difference may explain why hfq Sa cannot complement neither E. coli nor Salmonella typhimurium hfqs [START_REF] Večerek | The C-Terminal Domain of Escherichia Coli Hfq Is Required for Regulation[END_REF][START_REF] Rochat | Lack of Interchangeability of Hfq-like Proteins[END_REF]. Similarly, the mutant hfq in B. subtilis did not have any phenotype under 2000 growth conditions except a growth defect in rich medium in stationary phase [START_REF] Rochat | Tracking the Elusive Function of Bacillus Subtilis Hfq[END_REF]. Moreover, B. subtilis hfq also cannot complement S.

typhimurium hfq.

As Hfq Sa seems not involved in sRNA-dependent regulations, other staphylococcal proteins may be required for sRNA activities. For example, YbeY, a Sinorhizobium meliloti protein sharing structural similarities with Argonaute (an RNA-binding protein involved in RNA silencing in eukaryote) was found to act as Hfq and indeed, the mutant ybeY has similar phenotypes as those of hfq mutant [START_REF] Pandey | A Highly Conserved Protein of Unknown Function in Sinorhizobium Meliloti Affects sRNA Regulation Similar to Hfq[END_REF].

(A) (B)

Main RNases in S. aureus

Ribonucleases (RNases) contribute to RNA degradation and RNA processing. They can be divided into 2 groups: endoribonucleases (cleaving inside RNA molecules) and exoribonucleases (removing nucleotides from 5' or 3' ends of RNAs). RNases identified in S.

aureus are listed in Table 2. Main RNases, i.e. RNase III, RNase Y, RNase J1/J2 and PNPase, are discussed below.

RNase III: a major RNase involved in sRNA-dependent regulations

RNase III (encoded by rnc) is an endoribonuclease that belongs to a ubiquitous family of double-strand (ds)-RNA specific enzymes. In E. coli, RNase III is involved in various cell processes such as ribosomal RNA (rRNA) maturation (Srivastava et al. 1990;[START_REF] Deutscher | Chapter 9 Maturation and Degradation of Ribosomal RNA in Bacteria[END_REF], mRNA processing and its autoregulation (Bardwell et al. 1989). In addition, RNase III degrades mRNA-sRNA duplexes (Stead et al. 2011).

RNase III is the best characterized RNase n S. aureus. This 243-amino-acid enzyme was first characterized via its function in the agr system. sRNA-mRNA duplexes such as RNAIII-spa mRNA, RNAIII-rot mRNA, RNAIII-coa mRNA are degraded by RNase III (Boisset et al. 2007;Huntzinger et al. 2005;Liu et al. 2011;Novick et al. 1993) (Figure 25).

Type I toxin-antitoxin (TA) systems encode a poison and an antidote which is an asRNA that associates with the mRNA encoding the toxin (Fozo et al. 2008;Brantl 2012).

As toxin and antitoxin are expressed from opposite strands of a same DNA region, the two transcripts are complementary and form a duplex that can be targeted by RNase III. In B.

subtilis, RNase III is essential because it prevents the expression of toxins from type I TA systems (Durand et al. 2012). In S. aureus, the essentiality of RNase III is observed in specific backgrounds containing phages phi 11, phi 12, phi 13; these prophages are carrying type I TA systems (see chapter C).

Three studies on the role of RNase III in S. aureus were recently published. The first one is a transcriptome comparative analysis between a wild-type strain and its corresponding isogenic rnc mutant (Lasa et al. 2011). The rnc depletion mutant revealed an increased antisense transcription (74.2% in rnc compared with 49.2% in wild-type)

and a reduced number of short transcripts. This study demonstrates the role of RNase III in antisense-sense regulation and in reducing antisense transcription. The two other studies report coimmunoprecipitation assays of RNAs with RNase III and altered RNases III (Lioliou et al. 2012;[START_REF] Lioliou | In Vivo Mapping of RNA-RNA Interactions in Staphylococcus Aureus Using the Endoribonuclease III[END_REF]. Several RNAs were identified as RNase III substrates; its roles in rRNA and tRNA processings, and autoregulation of its own synthesis were confirmed. Moreover, RNase III was shown to be involved in mRNA turnover and mRNA-sRNA duplexes like in E. coli. Interestingly, RNase III was found to cleave the cspA (cold shock induced protein) 5'UTR (Figure 25).

RNase Y, RNase J1 and J2

In RNase J1 and RNase J2 (encoded by rnjA and rnjB, respectively) are 5' to 3' exonucleases and single-strand endonucleases [START_REF] Even | Ribonucleases J1 and J2: Two Novel Endoribonucleases in B.subtilis with Functional Homology to E.coli RNase E[END_REF][START_REF] Britton | Maturation of the 5′ End of Bacillus Subtilis 16S rRNA by the Essential Ribonuclease YkqC/RNase J1[END_REF]).

RNases J1 and J2 are 5'-monophosphate group specific and are inhibited by RNAs with a 5'-triphosphate group [START_REF] Deikus | Role of Bacillus Subtilis RNase J1 Endonuclease and 5′-Exonuclease Activities in Trp Leader RNA Turnover[END_REF]) [START_REF] De | Structural Insights into the Dual Activity of RNase J[END_REF]). The 5'-3' exonuclease activity of RNase J2 was weaker than the activities of RNase J1 or of the RNase J1/J2 complex. In B. subtilis, rnjA and rnjB are not essential [START_REF] Figaro | Bacillus Subtilis Mutants with Knockouts of the Genes Encoding Ribonucleases RNase Y and RNase J1 Are Viable, with Major Defects in Cell Morphology, Sporulation, and Competence[END_REF]). The rnjA mutant had longer doubling time (76 min) compared to the wild-type strain (26 min) but no change was observed in mutant rnjB. In addition, rnjA depletion affected sporulation, competence and cell morphology.

In contrast to B. subtilis, a study of essential genes by transposon mutagenesis concluded that rnjA and rnjB were essential in S. aureus [START_REF] Chaudhuri | Comprehensive Identification of Essential Staphylococcus Aureus Genes Using Transposon-Mediated Differential Hybridisation (TMDH)[END_REF]). However, single mutants rnjA, rnjB and double mutant rnjA/rnjB were obtained by allelic exchange in a more recent study [START_REF] Redder | New Range of Vectors with a Stringent 5-Fluoroorotic Acid-Based Counterselection System for Generating Mutants by Allelic Replacement in Staphylococcus Aureus[END_REF][START_REF] Linder | Transcriptome-Wide Analyses of 5'-Ends in RNase J Mutants of a Gram-Positive Pathogen Reveal a Role in RNA Maturation, Regulation and Degradation[END_REF]). These mutants cannot grow at 42 o C; it explained why these mutants were not obtained by transposon mutagenesis since a step was carried out at 44 o C. RNases J1 and J2 are essential under specific condition. rnjB leads to a stronger growth defect than rnjA. Interestingly, a mutation affecting RNase J1 active site leads to a phenotype equivalent to the rnjA deletion whereas a mutation affecting RNase J2 active site had no effect suggesting that RNase J2 plays a structural role. RNase J1 was shown to play a major role in RNA decay with the help of RNase J2 while both RNase J1 and J2 are responsible for cleaving precursor to mature 16s rRNA and RNase P ribozyme [START_REF] Linder | Transcriptome-Wide Analyses of 5'-Ends in RNase J Mutants of a Gram-Positive Pathogen Reveal a Role in RNA Maturation, Regulation and Degradation[END_REF].

PNPase

Polynucleotide phosphorylase (PNPase) is a bifunctional enzyme encoded by pnpA gene. PNPase is 3' to 5' exonuclease that uses inorganic phosphate P i instead of H 2 0 to degrade RNA and thus generates diphosphate nucleosides. PNPase can also have a second function as polymerase when the concentration of P i is lower than diphosphate nucleosides in the cell [START_REF] Deutscher | Exoribonucleases and Their Multiple Roles in RNA Metabolism[END_REF].

PNPase is not essential in both Gram-positive and Gram-negative bacteria.

However, pnpA mutants have cold-sensitive phenotype in E. coli and B. subtilis [START_REF] Wang | Properties of a Bacillus Subtilis Polynucleotide Phosphorylase Deletion Strain[END_REF].

In S. aureus, the pnpA mutant is also cold-sensitive confirming the important role of PNPase in cold shock adaptation [START_REF] Anderson | Messenger RNA Turnover Processes in Escherichia Coli, Bacillus Subtilis, and Emerging Studies in Staphylococcus Aureus[END_REF]. In addition, PNPase is involved in bulk RNA turnover: in wild-type strain, about 51% of transcripts are entirely degraded after 5 min of posttranscriptional arrest while only 17% are degraded in the pnpA mutant [START_REF] Anderson | Messenger RNA Turnover Processes in Escherichia Coli, Bacillus Subtilis, and Emerging Studies in Staphylococcus Aureus[END_REF].

Interestingly, it was shown that PNPase and RNase Y regulates the turnover of mRNAs involved in virulence in opposite manner [START_REF] Numata | CvfA Protein and Polynucleotide Phosphorylase Act in an Opposing Manner to Regulate Staphylococcus Aureus Virulence[END_REF]. The disruption of pnpA can suppress rny phenotypes (decreased hemolysin production and agr expression).

V. Selected samples of regulatory RNAs in some Firmicutes species 1. sRNA in the pathogenesis of Streptococcus

Most studies on Streptococci sRNAs concern three human pathogen species. Until now, 75 sRNAs were discovered in S. pyogenes [START_REF] Perez | A Genome-Wide Analysis of Small Regulatory RNAs in the Human Pathogen Group a Streptococcus[END_REF][START_REF] Patenge | Identification of Novel Growth Phase-and Media-Dependent Small Non-Coding RNAs in Streptococcus Pyogenes M49 Using Intergenic Tiling Arrays[END_REF][START_REF] Tesorero | Novel Regulatory Small RNAs in Streptococcus Pyogenes[END_REF]) and 179 sRNAs in S. pneumonia, respectively [START_REF] Tsui | Identification and Characterization of Noncoding Small RNAs in Streptococcus Pneumoniae Serotype 2 Strain D39[END_REF][START_REF] Kumar | Identification of Novel Non-Coding Small RNAs from Streptococcus Pneumoniae TIGR4 Using High-Resolution Genome Tiling Arrays[END_REF][START_REF] Acebo | Identification of 88 Regulatory Small RNAs in the TIGR4 Strain of the Human Pathogen Streptococcus Pneumoniae[END_REF][START_REF] Mann | Control of Virulence by Small RNAs in Streptococcus Pneumoniae[END_REF]). In addition, 197 regulatory RNAs were predicted in silico, of which 26 were valided whereas 39 riboswitches and cis-regulatory regions, 39 asRNAs and 47 sRNAs were found by using single nucleotide resolution RNAseq in the opportunistic pathogen S. agalactiae, or Group B Streptococcus [START_REF] Pichon | An in Silico Model for Identification of Small RNAs in Whole Bacterial Genomes: Characterization of Antisense RNAs in Pathogenic Escherichia Coli and Streptococcus Agalactiae Strains[END_REF][START_REF] Rosinski-Chupin | Single Nucleotide Resolution RNA-Seq Uncovers New Regulatory Mechanisms in the Opportunistic Pathogen Streptococcus Agalactiae[END_REF].

In S. pyogenes, Pel, FasX and RivX are three characterized sRNAs involved in virulence. fasX (fibronectin/fibrinogen-binding/hemolytic-activity/streptokinase-regulator-X) is the last gene of the fasBCAX operon and it regulates its own operon. In addition, FasX negatively regulates the expression of fbp54 (fibronectin binding protein), and mrp (fibrogen binding protein) [START_REF] Kreikemeyer | Group A Streptococcal Growth Phase-Associated Virulence Factor Regulation by a Novel Operon (Fas) with Homologies to Two-Component-Type Regulators Requires a Small RNA Molecule[END_REF]. It also interacts with the 5'-end of ska mRNA (secreted plasminogen activator streptokinase) to stabilize the transcript and stimulate its translation (Ramirez-Peña et al. 2010) (Figure 28).

sRNA in the pathogenesis of Clostridium

Clostridium is a large genus containing around 100 species. This genus not only includes human and animal pathogens but also many strains involved in cellulose degradation, the carbon cycle, bioremediation and biotechnology. sRNAs were identified in three Clostridium species: 251 sRNAs (94 trans-encoded, 91 cis-encoded sRNA and 66 riboswitches) in the human pathogen Clostridium difficile (Soutourina et al. 2013), 159 sRNAs in Clostridium acetobutylicum [START_REF] Venkataramanan | The Clostridium Small RNome That Responds to Stress: The Paradigm and Importance of Toxic Metabolite Stress in C. Acetobutylicum[END_REF]) and 36 sRNAs in Clostridium ljungdahlii [START_REF] Tan | RNA-Seq-Based Comparative Transcriptome Analysis of the Syngas-Utilizing Bacterium Clostridium Ljungdahlii DSM 13528 Grown Autotrophically and Heterotrophically[END_REF].

An interesting example is the regulation of the ubiGmccBA operon in C.

acetobutylicum. This operon is involved in the conversion of methionine and cysteine.

Four antisense RNAs with their length varying from 264 nt to 1000 nt are transcribed from the downstream region of the ubiGmccBA operon. Their expression is controlled by a Sbox riboswitch; these different antisenses interfere with ubiGmccBA mRNA by basepairing [START_REF] André | S-Box and T-Box Riboswitches and Antisense RNA Control a Sulfur Metabolic Operon of Clostridium Acetobutylicum[END_REF]) (Figure 29).

Another example in the food poisoning pathogen Clostridium perfringens, is VR-RNA (VirR-regulated RNA), a sRNA positively regulated by the VirR/VirS TCS [START_REF] Shimizu | Clostridial VirR/VirS Regulon Involves a Regulatory RNA Molecule for Expression of Toxins[END_REF][START_REF] Ohtani | The VirR/VirS Regulatory Cascade Affects Transcription of Plasmid-Encoded Putative Virulence Genes in Clostridium Perfringens Strain 13[END_REF]. VR-RNA activates many genes such as pfoA (theta toxin), plc (alpha-toxin), cpd (2',3'-cyclic nucleotide phosphodi-esterase), ptp (protein tyrosine phosphatase) and colA (kappa-toxin or collagenase) and represses the operon ycgJ-metB-cysK-luxS which includes ycgJ (encoding a hypothetical protein), metB (encoding cystathionine gamma-lyase), cysK (encoding cysteine synthase), and luxS (encoding the autoinducer 2 synthase) [START_REF] Shimizu | Clostridial VirR/VirS Regulon Involves a Regulatory RNA Molecule for Expression of Toxins[END_REF]. Interestingly, VR-RNA directly binds to the 5'UTR of colA mRNA and induces the cleavage of this mRNA. The cleaved mRNA is stable and hence proficient for translation [START_REF] Obana | Stabilization of Clostridium Perfringens Collagenase mRNA by VR-RNA-Dependent Cleavage in 5??? Leader Sequence[END_REF]) (Figure 29).

sRNA in the pathogenesis of Listeria monocytogenes

In L. monocytogenes, 113 sRNAs and 70 asRNAs were discovered by performing comparative transcriptomes with its relative non-pathogenic L. innocua [START_REF] Wurtzel | Comparative Transcriptomics of Pathogenic and Non-Pathogenic Listeria Species[END_REF]. Combine with previous study [START_REF] Mraheil | The Intracellular sRNA Transcriptome of Listeria Monocytogenes during Growth in Macrophages[END_REF][START_REF] Oliver | Deep RNA Sequencing of L. Monocytogenes Reveals Overlapping and Extensive Stationary Phase and Sigma B-Dependent Transcriptomes, Including Multiple Highly Transcribed Noncoding RNAs[END_REF][START_REF] Toledo-Arana | The Listeria Transcriptional Landscape from Saprophytism to Virulence[END_REF]), total 134 sRNAs and 86 asRNAs were found in this bacterium. In Gram-positive, the interaction of sRNAs and their target seems not to require the RNA chaperone Hfq, but there is an exception: LhrA [START_REF] Nielsen | Defining a Role for Hfq in Gram-Positive Bacteria: Evidence for Hfq-Dependent Antisense Regulation in Listeria Monocytogenes[END_REF]).

The chitinase ChiA is an enzyme that catalyzes chitin hydrolysis and is also involved in L. monocytogenes pathogenesis in a mice model [START_REF] Chaudhuri | Chitinases Contributes to Listeria Monocytogenes Pathogenesis[END_REF]. The liver and spleen colonization was significantly reduced with chiA mutant as compared to parental strain. LhrA sRNA regulates chiA mRNA and two hypothetical mRNAs (lmo0850 and lmo0302) [START_REF] Nielsen | Defining a Role for Hfq in Gram-Positive Bacteria: Evidence for Hfq-Dependent Antisense Regulation in Listeria Monocytogenes[END_REF]) (Jesper S. Nielsen et al. 2011). LhrA sequester the RBS of chiA mRNA and inhibit its translation initiation (Figure 30). PrfA is a L. monocytogenes regulator of virulence active at 37 o C (host humanbody temperature) but not at 30 o C [START_REF] Johansson | An RNA Thermosensor Controls Expression of Virulence Genes in Listeria Monocytogenes[END_REF]. Its expression is controlled by a RNA thermoswitch located in the 5'UTR of prfA mRNA. Moreover, the prfA thermoswitch is also linked to an S-adenosyl methionine (SAM) riboswitch element A (SreA) [START_REF] Loh | A Trans-Acting Riboswitch Controls Expression of the Virulence Regulator PrfA in Listeria Monocytogenes[END_REF]). When the level of SAM is high (as inside the host), it binds to SreA, resulting in a conformational change of the RNA structure. SreA then acts in trans, binding to prfA thermoswitch and repressing its translation. Therefore, the expression of PrfA is tightly controlled during infection process due the combined activities of prfA thermoswitch and SAM-metabolite riboswitch integrating the temperature and the presence of SAM, respectively (Figure 31).

sRNA in Bacillus subtilis

FsrA was the first characterized sRNA in B. subtilis [START_REF] Gaballa | The Bacillus Subtilis Iron-Sparing Response Is Mediated by a Fur-Regulated Small RNA and Three Small, Basic Proteins[END_REF]. FsrA is homologous to RyhB in E. coli which is involved in iron metabolism and storage. FsrA is a global regulator controlling genes related to iron such as sdhCAB (succinate dehydrogenase) and citB (aconitase). However, unlike RyhB in E. coli, FsrA does not require the RNA chaperone Hfq. On the other hand, FsrA requires the Fur-regulated small proteins FbpA, FbpB and FbpC. At low iron concentration, FsrA represses the expression of lutABC operon (encoding iron sulfur cluster-containing enzymes) by binding to lutA mRNA translation initiation region. The interaction FsrA/lutABC is facilitated by FbpB. FbpB not only facilitates the interaction but also recruits the RNA degradosome.

B. subtilis has also a dual-function sRNA named SR1. SR1 is only expressed in gluconeogenic conditions. In glycolytic conditions, SR1 is repressed by a catabolite control protein A (CcpA) and a control catabolite protein of gluconeogenic genes (CcpN). The first function of SR1 is to base-pair with the transcriptional activator ahrC mRNA. The interaction involves 7 complementary regions (100 nt downstream from RBS of ahrC mRNA), hence remodeling the mRNA to inhibit the translation initiation. AhrC is the transcriptional activator of two arginine catabolism operons RocABC and RocDEF.

Consequently, SR1 indirectly controls these two operons. The second function of SR1 is associated with a 39 amino-acid peptide, called SR1P, encoded by SR1, that interacts with gapA mRNA to stabilize it by an unknown mechanism (Figure 32).

sRNAs in the pathogenesis of Enterococcus faecalis

E. faecalis is an opportunistic human pathogen that belongs to the Enterococci family. This bacterium is hospital-acquired and multi-drug resistant. More than 100 sRNAs were identified in E. faecalis through various approaches such as bioinformatic prediction, 5' and 3' RACE mapping, microarray and northern blot [START_REF] Livny | High-Throughput, Kingdom-Wide Prediction and Annotation of Bacterial Non-Coding RNAs[END_REF][START_REF] Fouquier | A Simple and Efficient Method to Search for Selected Primary Transcripts: Non-Coding and Antisense RNAs in the Human Pathogen Enterococcus Faecalis[END_REF][START_REF] Shioya | Genome-Wide Identification of Small RNAs in the Opportunistic Pathogen Enterococcus Faecalis V583[END_REF][START_REF] Innocenti | Whole-Genome Mapping of 5' RNA Ends in Bacteria by Tagged Sequencing: A Comprehensive View in Enterococcus Faecalis[END_REF]. Among them, ef0408-0409 sRNA is homologous to RNAII which is a component of a type I component TA system; its deletion increased virulence, and organ colonization in a mouse model, and survived better in macrophage. In addition, mutant ef0408-0409 grew better in oxidative and osmotic stress conditions and was more resistant to acid. In contrast, three other mutants (ef0605-00606, ef1368-1369 and ef3314-3315) were less virulent than the wild-type strain [START_REF] Michaux | Involvement of Enterococcus Faecalis sRNAs in the Stress Response and Virulence[END_REF]). This study showed a connection between stress resistance and pathogenicity.

Recently, a new model came out revealing a riboswitch-regulated sRNA that controls gene expression by sequestering a response regulator in E. faecalis (DebRoy et al.

2014) (Figure 33). This original regulation was also observed in L. monocytogenes [START_REF] Mellin | Sequestration of a Two-Component Response Regulator by a Riboswitch-Regulated Noncoding RNA[END_REF]. Briefly, this system regulates ethanolamine (EA) metabolism as a source of carbon and nitrogen. Many genes involved in ethanolamine utilization (eut) are located on the same locus and expressed only when both ethanolamine and vitamin B12 are present.

E. faecalis responds to the presence of EA via the EutW/EutV TCS. In the presence of EA, the response regulator EutV is phosphorylated by the EutW histidine kinase [START_REF] Baker | Transcription Antitermination by a Phosphorylated Response Regulator and Cobalamin-Dependent Termination at a B12 Riboswitch Contribute to Ethanolamine Utilization in Enterococcus Faecalis[END_REF]. This active EutV forms dimers and binds RNA hairpins expressed from the eut locus. Active EutV acts as an "anti-terminator". However, the transcription of the eut operon is still turned off when vitamin B12 is not present because EutV is sequestered by a riboswitch containing a noncoding RNA. When vitamin B12 is present, it binds to the riboswitch and changes its structure hence forming a terminator. Thus, the transcription of the noncoding RNA stops freeing the protein EutV. Therefore, EutV promotes the expression of the eut operon only when both ethanolamine and vitamin B12 are present (Figure 33).

AIM OF THE THESIS

In S. aureus, about 200 regulatory RNAs (sRNAs) were identified but up to date, their functions in most cases are unknown.

1) The main goal to this thesis was to setup a methodology to determine phenotypes associated with S. aureus sRNAs genes on a large scale. A strategy was developed to evaluate the adaptative ability of a collection of sRNA gene mutants to various tested environmental conditions by performing competitive fitness experiments. 14 mutants with a chromosomal tagged deletion among 39 tested were either accumulating or disappearing in the 13 tested conditions. The observed phenotypes in these mutants are indications to help to determine the functions associated with these sRNAs (Chapter A).

2) An important step to determine the sRNA functions is the identification of sRNA targets. sRNAs usually associate by base-pairing with targeted mRNAs to affect their expression. Several computational methods propose lists of putative sRNA targets based on the identification of sRNA/RNA pairing regions. However, the pairing rules are not fully understood and these methods generate numerous false positive candidates and sometimes do not retain true positive targets. Therefore, we developed a robust procedure to identify reliably sRNA targets based on synthetic sRNAs that were used in vitro as bait to trap their corresponding targets which were subsequently identified by deep sequencing. The second chapter of this thesis reported the method and its application to four staphylococcal sRNAs RsaA, RsaE, RsaH and RNAIII (Chapter B).

The binding of sRNAs to their targets mRNAs usually affect their stability by recruiting RNase(s). In S. aureus, RNase III encoded by rnc gene is a major RNase involved in the degradation of sRNA-mRNA duplexes. RNase III was reported as nonessential in S. aureus. In chapter C, we report that the rnc gene is essential in strains containing prophages carrying type I toxin/antitoxin systems.

73

CHAPTER A1

Competition experiments with regulatory RNA gene mutants in Staphylococcus aureus: identification of a 3'UTR contributing to optimal growth at low-temperatures

Introduction

Staphylococcus aureus is a major human and animal opportunistic pathogen. It causes syndromes ranging in severity from minor skin infections to life threatening diseases such as infective endocarditis and necrotizing pneumonia [START_REF] Lowy | Staphylococcus aureus infections[END_REF]. The bacterium proliferation and pathogenicity are due to rapid adaptations to environmental conditions and controlled expression of virulence factors [START_REF] Arvidson | Regulation of virulence determinants in Staphylococcus aureus[END_REF][START_REF] Bronner | Regulation of virulence determinants in Staphylococcus aureus: complexity and applications[END_REF][START_REF] Cheung | Regulation of virulence determinants in vitro and in vivo in Staphylococcus aureus[END_REF]). Numerous elements orchestrate the adaptive regulatory networks. Among them, sigma factors, regulatory proteins are contributing to transcriptional regulations, and a second line of control is posttranscriptional in which regulatory RNAs are essential contributors (Felden et al. 2011;[START_REF] Rochat | Gene expression control by selective RNA processing and stabilization in bacteria[END_REF]Bonnin and Bouloc 2015).

Bacterial regulatory RNAs are divided in two categories, cis-and trans-acting: the first one exerts its regulatory activity on associated or interdependent adjacent RNA sequences, while the second one base-pairs with independent RNAs or bind to proteins. Trans-acting RNAs targeting RNAs i) that are expressed from a complementary strand of another RNA (usually an mRNA) are called asRNAs (for antisense RNAs) (Georg and Hess 2011) and ii) those expressed from DNA sequence with no transcript on the complementary strand are usually referred to as sRNAs (for small RNAs) (Storz et al. 2011;[START_REF] Guillet | Emerging Functions for the Staphylococcus Aureus RNome[END_REF].

Bacterial sRNAs are often between 50 to 300 nucleotides, non-coding, conditionally expressed (e.g., upon specific growth stresses or growth phases) and their association by base-pairing to mRNA targets affects the stability and/or translation of the target.

In S. aureus, RNAIII is the paradigm for a growing number of sRNAs associated with virulence (Novick and Geisinger 2008). Induced at high cell density by a quorum sensing regulation, RNAIII modulates the expression of numerous genes contributing to staphylococcal virulence. However, S. aureus has hundreds of regulatory RNAs for which the function and mechanism is mostly unknown (Felden et al. 2011). As sRNAs often contribute to the "fine-tuning" of gene expression, their associated phenotypes are difficult to determine. For example, no obvious growth phenotype was found for the absence of RsaE in S. aureus, a widely conserved sRNA in bacteria which down-regulates the Krebs cycle and folate metabolism (Geissmann et al. 2009;Bohn et al. 2010). However, minor sRNA-mediated phenotypes conferring modest advantages may nevertheless affect bacterial fitness and emerge as dominant traits after a few generations under selective pressure.

Finding phenotypes associated with sRNA gene deletions usually require testing of many conditions for each mutant, with no assurance of success. To tackle this problem for S.

aureus sRNAs, we used an alternative method based on the detection of barcoded deletions which was developed in yeast (Shoemaker et al. 1996) and also apply to bacteria (Mazurkiewicz et al. 2006;Hobbs et al. 2010;[START_REF] Hobbs | Competition assays using barcoded deletion strains to gain insight into small RNA function[END_REF]. We adapted the protocol to deep sequencing technology. We tested three growth conditions in triplicate with 39 tagged S. aureus sRNA mutants. We identified nine sRNA deletion mutants that resulted in the accumulation or disappearance of strains carrying them in at least one of the tested conditions. The strategy develop will be instrumental to identify sRNA-dependent phenotype and to find their functions.

Results and Discussion

Identification of mutants within a population having altered growths: general principal.

The goal is to the follow the amount of each mutant within a mutant collection growing under different conditions. Comparison to a reference condition allows to identify mutations conferring selective advantages or disadvantages with respect to the tested growth conditions. Each mutant is recognized and counted thanks to specific DNA tag sequences.

The first step for this method was to obtain a large collection of tagged mutants in the background of interest. Then, mutant sets were grown in different conditions, the genomic DNA from these mixed populations were extracted, tags were PCR-amplified and the proportion of each specific tag was determined (Figure 1).

Construction of a set of tagged sRNA-deletion genes in S. aureus.

Tagged deletions were constructed in HG003, a NCTC8325 derivative in which rsbU and tcaR mutations were repaired and that is used as a model strain for staphylococcal regulation studies (Herbert et al. 2010). Loci replacements were performed by two-step homologous recombinations with integration and excision at targeted loci of a conditionally replicative plasmid containing the sequence the desired sequence. We used pMAD2 (Bonnin et al., unpublished results), a replication thermo-sensitive plasmid derived from pMAD (Arnaud et al. 2004). In order to follow all mutated strains within a population of different mutants, each deleted region was replaced by a tag sequence containing a specific 40-mer DNA sequence of each deletion (Shoemaker et al. 1996). The 40-mer, which is a DNA barcode identifier, is flanked on both sides by 26-mer sequences that are identical for all tags (Figure 1 and S4). The 26-mer sequences allow PCR amplifications of each barcode sequences with the same two primers. We generated the DNA barcode sequences as followed. A DNA oligonucleotide made of the forward priming 26-mer region, a 40-mer random sequence and a reverse priming 26-mer region was PCR amplified, cloned into a plasmid and transformed into E. coli. The inserted sequences of about hundred transformants were characterized by DNA sequencing and those with adequate inserts were used to mark the deletions (Table S4). Efficient recombination of pMAD2 derivatives in S. aureus requires homologous fragment of about 1 kb. We therefore cloned into pMAD2, i) DNA tags (generated as described above) flanked on both sides ii) by about 1kb sequences of the surrounding deleted regions. The pMAD2 derivatives with confirmed expected inserts (by DNA sequencing) were transformed into RN4220, extracted and transformed into HG003 to perform allelic replacements as described (Arnaud et al. 2004). All gene substitutions constructed were with non-antibiotic marker remaining (Material and Methods).

sRNA genes selected for disruption were chosen based on data available when the project started (e.g. (Felden et al. 2011)). We retained those corresponding to apparent bona fide sRNAs. Deleted regions comprised, when information were available, promoter regions and full-length of sRNA genes. As i) the limits of many sRNA genes were unknown, ii) constructed deletions depends on the cloning of flanking regions and iii) S. aureus is 32%

GC with long AT rich regions, some constructed deletions were either longer or shorter than the sRNA genes (Table S3). Recent deep sequencing data indicate that some RNA sequences retained for our study and initially considered as sRNA are 5' or 3' UTR of mRNAs. Altogether, 39 strains, each one containing a different tagged deletion, were constructed (Table S1)

Competition experiments

Each mutant strain was grown individually in a rich medium and assembled together in the same amount (normalized to OD 600 ) to generate a starting culture of a tag deletion set. The procedure was repeated three times to generate three independent sets. Competition experiments were performed by diluting 1000 times the three tag deletion sets into a fresh culture medium and growing them in the tested conditions. A first sampling was performed during exponential phase when cultures reached OD 600 0.6 to 0.7 (Sampling 1). The remaining cultures left to grow and the day after, the overnight cultures were diluted 1000 times into a fresh culture medium and grown again in the same tested conditions. A second sampling was performed when the cultures reached OD 600 0.6 to 0.7 (Sampling 2).

As many sRNA genes are expressed during stationary phases, Sampling 2 should allow the detection of phenotypes with sRNAs expressed preferentially at high density. In addition, phenotypes detected in Sampling 1 may be more pronounced in Sampling 2. In order to evaluate the proportion of each mutant within a mix population, the proportion of each DNA barcode were evaluated. In most previously published fitness protocols, genomic DNA from mixed populations was extracted, the tags were PCR-amplified and the proportion of each specific tag was determined by hybridizing the labeled PCR products on dedicated DNA arrays (Mazurkiewicz et al. 2006). These experiments are tedious and expensive, as each tested condition requires at least one array. We decided to count the PCR products by deep sequencing rather than by arrays. However, as all growth conditions (including triplicates) have to be discriminated, in principle, these experiments would require constructing as many DNA-seq banks as tested conditions increasing significantly the cost of the method. We therefore adapted the protocol as follow. PCR products of each experiment were obtained with two primers having 5'-extensions of 5 nucleotides; these "experiment identifiers" were specific of each sample counted (Table S5). The same quantity of PCR products from different conditions were mixed together. In As prove of principle, two growth conditions were tested, 42°C and 20°C. Barcode sequences from Sampling 1 and 2 in both conditions were identified and counted for the three assemble sets of sRNA-tagged deletions. Barcode sequences were also counted for samples grown at 37°C. The frequency of each mutant within the remaining population of Samplings at 42°C and 20°C were determined and normalize to the 37°C conditions.

Consequently the data at high and low temperature are relative to 37°C. A standard deviation for each barcode tag frequency was determined from the results of triplicates.

Mutants were considered either accumulate or disappear in the tested condition when a significant five-fold difference was observed with the reference condition.

At 42°C, in Sampling 1, Δsau30, Δsau6836 and ΔrsaH were significantly underrepresented (Figure 2A) while in Sampling 2, only Δsau6428 was found significantly underrepresented (Figure 2B). In Sampling 2, Δsau30, Δsau6836 and ΔrsaH mutants are still strongly underrepresented when the results from the 3 sets are average, however, with an unacceptable standard deviation.

At 20°C in Sampling 1, ΔrsaOV mutant was the most underrepresented followed by Δsau60 (Figure 3A). In Sampling 2, five mutants were found significantly underrepresented, ΔrsaOV, ΔrsaD, Δteg49, Δsau60 and Δsau6528, with ΔrsaOV still the most underrepresented (Figure 3B).

Mutants with significant growth disadvantage at 42°C or 20°C revealed by these competition experiments were grown individually either at low or high temperature and compared to the parental strain.

In individual culture, the sau30 deletion led to a growth defect at 42°C (Figure 4A) which

was not present at 37°C (Figure 4B). The Sau30 sRNA (alias SSR154) was reported in two studies (Anderson et al. 2006;Abu-Qatouseh et al. 2010). The gene is located between SAOUHSC_02483 (cbiO encoding the subunit of a putative cobalt transporter) and SAOUHSC_02484 (rplQ encoding the 50S ribosomal protein L17). However, deepsequencing transcriptome data indicates that Sau30 is possibly a 3'UTR part of rplQ mRNA rather that a sRNA per se (Figure S1). The sau30 deletion constructed encompasses a large region that could affect cbiO gene. In individual cultures, no growth difference were observed between Δsau6836 ΔrsaH and the parental strain at 42°C, possibly because i) the growth differences are small and cannot be revealed by simple growth curves or ii) the growth defect may depends on the presence of other strains.

The ΔrsaOV, ΔrsaD, Δteg49, Δsau60 and Δsau6528 mutants had significant slower growth rate than the parental strain in individual culture at low temperature (Figure 5A) in contrast to 37°C (Figure 5B). As the growth defect was much more pronounced for the rsaOV, this mutant was retained for further studies.

The 3'UTR of cwrA is required for optimal growth at low temperature

The RsaOV sRNA (alias Sau40) was reported in two studies (Abu-Qatouseh et al. 2010;Bohn et al. 2010). Its corresponding gene is located between SAOUHSC_02872 (cwrA) and SAOUHSC_02873 (encoding the subunit of a putative copper transporter).

We first try to complement unsuccessfully the rsaOV growth defect by a plasmid carrying the putative rsaOV gene (Figure 6). As for Sau30, deep-sequencing transcriptome data indicates that RsaOV may not be a sRNA per se, but more likely the 3'UTR end of the cwrA mRNA (Figure S2). These observations raised the possibility that the cwrA 3'UTR would be required for an efficient cwrA expression. Several plasmids were constructed to identify the required sequence to compensate the ΔrsaOV cold deficiency (Figure 7).

Plasmids carrying the cwrA promoter i) and the cwrA open reading frame (without rsaOV),

or ii) rsaOV (without cwrA) did not rescue the ΔrsaOV mutation. However, the plasmid carrying the complete region (cwrA promoter + cwrA open reading frame + rsaOV) complemented the ΔrsaOV growth defect a low temperature (Figure 6). To support the hypothesis that the deletion was rescued by the expression of cwrA, the cwrA initiation codon (ATG) of the complementing plasmid was mutated to a stop codon (TAA) (Figure 7); the resulting plasmid lost its ability to complement the ΔrsaOV cold deficiency (Figure 6).

We concluded that rsaOV may be required to prevent the cwrA mRNA degradation and/or to stimulate its translation.

The cwrA gene is so far poorly characterized. It encodes a putative 63 amino-acid protein of unknown function. The combined analysis of several transcriptome studies of S. aureus treated with antibiotics targeting the cell wall revealed 15 genes always upregulated and 2 downregulated [START_REF] Kuroda | Two-component system VraSR positively modulates the regulation of cell-wall biosynthesis pathway in Staphylococcus aureus[END_REF][START_REF] Utaida | Genome-wide transcriptional profiling of the response of Staphylococcus aureus to cell-wall-active antibiotics reveals a cell-wall-stress stimulon[END_REF][START_REF] Mcaleese | Overexpression of genes of the cell wall stimulon in clinical isolates of Staphylococcus aureus exhibiting vancomycin-intermediate-S. aureus-type resistance to vancomycin[END_REF][START_REF] Mccallum | Strain dependence of the cell wall-damage induced stimulon in Staphylococcus aureus[END_REF]) belonging the cell wall stimulon [START_REF] Utaida | Genome-wide transcriptional profiling of the response of Staphylococcus aureus to cell-wall-active antibiotics reveals a cell-wall-stress stimulon[END_REF]). Among them, cwrA is strongly upregulated. Its expression was studied with transcriptional gene fusions between cwrA and a bacterial lux cassette (Balibar et al. 2010). These experiments showed that cwrA expression was induced by cell wall-targeting antibiotics (e.g. vancomycin, oxacillin, penicillin) but not by antibiotics with other targets. However, because these results are obtained with gene fusions, they cannot take in account a possible regulatory role of the 3' UTR.

Material and methods

Bacterial strains, plasmids and growth conditions

Strains and plasmids used in this study are listed in Tables S1 andS2, respectively.

Allelic replacements of S. aureus genes were performed using pMAD2 derivatives. pMAD2

(GenBank accession number: KT323982) is a shuttle vector derived from pMAD (Arnaud et al. 2004) with a thermosensitive replication origin in S. aureus. pMAD2 is available for scientific community as Addgene plasmid N° 67682 (https://www.addgene.org/).

Complementation studies were performed using derivatives from pCN38, a cloning shuttle vector [START_REF] Charpentier | Novel cassettebased shuttle vector system for gram-positive bacteria[END_REF]). The tag library use to mark the sRNA gene deletions was cloned into pJET (GenBank/EMBL Accession number EF694056).

Staphylococcus aureus strains RN4220 and HG003 (Herbert et al. 2010) were routinely grown with aeration at 28°C, 37 o C and 42°C in BHI broth or BHI agar. Escherichia coli DH5αZ1 was grown in LB broth or LB agar. When appropriate, the following antibiotics were used: erythromycin (0.5µg/ml), chloramphenicol (5µg/ml) for S. aureus strains and ampicillin (100µg/ml), chloramphenicol (20µg/ml) for E. coli DH5α.

DNA manipulation

Plasmids were extracted using NucleoSpin Plasmid Quick Pure kit (Macherey-Nagel, Düren, Germany), following manufacturer protocol with an additional step for S. aureus:

cells

Generation of DNA Tag (barcodes) library

To mark specifically each constructed gene deletion, a library of DNA tags was generated.

The oligonucleotide "tag_random" containing a 40-mer random sequence between two non-random 26 nucleotide long regions was PCR-amplified using primers tag_F and tag_R (See Table S3, Supplementary data). PCR products were cloned into pJET plasmid using

CloneJET PCR Cloning Kit following manufacturer instructions (Thermo Scientific).

Ligation products were transformed into DH5αZ1, plasmids were extracted from about 100 clones and the inserts were identified by DNA sequencing of the inserts. The sequence of the retained tags is listed in Table S4.

Construction of tagged sRNA deletion in S. aureus HG003

Locus replacements in HG003 were performed by a two-step homologous recombination with integration and excision of conditionally replicative pMAD2 derivatives at targeted loci.

pMAD2 derivatives contained sequences (about 1 kb) of upstream and downstream flanking regions of the deleted locus and in between these two regions, a given tag sequence.

HG003 rsaA tagged deletion was constructed as followed. The upstream and downstream rsaA sequences were PCR-amplified from HG003 chromosomal DNA using primers RsaA-UpF/RsaA-UpR and RsaA-DwF/ RsaA-DwR, respectively (for primers, see Table S3). The tag1 sequence was PCR-amplified from pJET-tag1 (for tag sequences, see Table S4).

pMAD2 was PCR-amplified using pMAD-F/pMAD-R primers. pDErsaA::tag1 (for DEletion of rsaA substituted by tag1) was obtained by assembling the four PCR fragments as described (Gibson et al. 2009). The assembled mix was used to transform E. coli DHZ1.

Usually, two plasmids isolated from DH5αZ1 were verified by DNA sequencing of inserts.

As HG003 is not permissive for plasmids originating from E. coli, a confirmed plasmid was used to transform RN4220, extracted from RN4220 and transferred into HG003. Allelic chromosome/plasmid exchanges leading to chromosomal loci substitution by tag sequences were performed in HG003 as described (Arnaud et al. 2004) and verified by PCR tests. All forty tagged deletion mutants (Table S1) were constructed in the same way using the appropriate pMAD2 derivatives (for primers use to plasmid constructions, see Table S3).

Fitness assays/Competition assays/Bacterial competition assays

Each sRNA tag-mutant was inoculated separately in BHI broth and grown for 16h at 37 o C with aeration. Overnight cultures were diluted 1:1000 in fresh BHI broth and grown to OD 600  0.6 -0.7. The forty cultures of mutated strains were pooled together with the same quantity for each one and stored in aliquot at -80 o C. Three sets of aliquots were assembled, with each sRNA tag-mutant culture originating from three independent clones.

The three sets were used to perform each experiment in triplicate.

The tagged mutant sets were used to test the fitness of each mutation in various conditions as follow. For a given set, one aliquot was keep (time 0), one was grown in standard condition (BHI broth, 37 o C with aeration) and the others aliquots were grown in various stress conditions. Except time 0, aliquots for competition assays were diluted 1:1000. Sixteen competition conditions were tested and analyzed. Each experimental condition was performed in triplicate using the three independent sets. To identify sRNAs that would affect S. aureus growth in cold or warm conditions, each triplicate sets were grown at 20 o C or 42 o C under aeration. Bacteria cultures were sampled for each competition assay at OD0.6. The remaining cultures were grown overnight, diluted 1:1000 the day after in the same medium, grown in the same condition and samples were harvested at OD0.6.

DNA-seq library, high-throughput sequencing and data analysis

Chromosomal DNA was extracted from each culture as described above and tagged sequences were amplified. To construct only one deep sequencing Illumina bank with many samples and to be able to discriminate each experiment, we use specific primers for each experiment differing in the sequence of their last five 5' nucleotides (Table S5). The primer remaining part contained the conserved region for amplification of all tags.

Sequencing bank on PCR amplified DNA fragments for Illumina sequencing were constructed following manufacturer instruction. They were paired-end sequenced (2x 50 nt) by the CNRS IMAGIF platform (Gif-sur-Yvette, France).

Sequencing data was analyzed by using tools given by bioinformatics plateform MIGALE (Jouy-en-Josas, France). Briefly, two paired-end libraries were combined and each experiment/competition assay was separated by splitting 5-nucleotide-experiment-specific barcodes/primers at both ends. In each sample, the numbers of Tag sequences were verified corresponding to all mutant strains. We performed normalization by comparing with control samples and finally did statistical analysis for 3 biological replicates.

Growth curves

Growth curves were done in triplicate in 96-Well multiwell plates covered with a semipermeable film (4titude, Bagneux France) under constant vigorous shaking using the microplate reader CLARIOstar (BMG Labtech, Ortenberg, Germany). Overnight culture of S. aureus strains were diluted at 1:1000 in 200 l of BHI medium with antibiotic when necessary. The growth curve was measured by OD 600nm every 15 minutes for 18 hours at either 25°C, 37 o C or 42 o C.

Disclosure of Potential Conflicts of Interest

None to declare. OD 600 was measured periodically.

GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCTCACCACCTCCAACTATCC CGAGAACACTATCACTCTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag2 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCACCACTACATCACTCTCAAA ACCCCGAGATAGCGCTCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag3 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGATACCCCAAGCAATCACAAC ACCGCAACAGATCTAACAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag4 GGTCTCATGTGTTGTGGGGTACAGCAATGACAAGCTTGGTTTGCTCTGGCGATATTGGT CTATCGGTGGGTAGCTAGAAGCTTATTGCATAGCTGCGTATGGATCTCAGAGACC tag5 GGTCTCATGTGTTGTGGGGTACAGCAATGACAAGCTTCGTTGTCGGTGGTTTGCGCGAG ATTTAGGGGGGTCGAGGGAAGCTTATTGCATAGCTGCGTATGGATCTCAGAGACC tag6 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTCTATCTAAAAACACCCCAAT AACCAACTAACTAACTCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag7 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTATCGAGAAATCCCTCGCAATAT CTATATCCATACCTCGCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag8 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCTCCCAATATCTCACCAGAC CCCCCAACCTCGCACCCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag9 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTACAGCTAGCTCACTCCCACCAC CCACACAGCAAAAACTCGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag10 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTCCCAAAACCTCTCCAGCCAA CTCAACAACTCGCTATCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag11 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTACATATCCCGCCAGCCCCAAAA AGCGCAAAACCCCGACCGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag12 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTACCCATAGACCTCCAACGAGCT AAATCACGCGACCCCTCTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag13 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTACACCCCACGCGCAAACCCCAT AAACAGAACCCTCCACCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag14 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAACGCTAACAACCTCCCGACAA AGACCTAGACACCAACAGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag15 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAAACCCCACCCCAGATACATCT CACGATCCACACCTACCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag16 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCAATAGACATACCGAGATCTAA CAATAACACCCCCGAACTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag17 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTATACCCCGCGCCCTATCAAA ATCCCTCCCGCAAGCCCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag18 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCAGCCCCCACACGCGATAGAC AAATAGACCTAGCGACACAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag19 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCAAATCCCACTCCCCAGCCCG AGAAAGCTAGACCCCGCTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag20 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCATCCATAGCTCTATAGCCCG CAACCAAAACCTCGATACAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag21 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTCTCCACCGACACCCCCCACA ATCCAGAAAACACCCTCGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag22 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCGCGAAAGACACAGCTACCC CCACAAAAATCCCCCACTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag23 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAACTAGACCACCAGAGAAAGCT CCAAATACCCATCTATACAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag24 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAGAGCCCTCGAGAAACAAAGCA AACCCGAGATACACATCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag25 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAGACAGCTCCCCATCCACCCCA ATCACGCGATCCCGCCAGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag26 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGAACGAGCGAGACATAACGAT CTCAAGCGCCAACGCACTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag27 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTCCCCCACGCAAGACCCAACC ACACATCTACCCAGATAGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag28 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGAGAACACCCCCGCTCGAACT CTCTATCCCCCAACAACGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag29 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGCTAGCTCTCCATCCCACAAG AACGAACTACCCCCCAAAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag30 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCTCCCAAAACCCAAACCTCG CACGATCACGCCCCCTCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag31 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTACCAACCGCGCCCCACCACCCC CACAAACCAGCAACAAATAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag32 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGAAATCTAACCCAATACCAAC AGCCAGCTCGATCGCACCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag33 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGCGCGCGACCACCAGCCCCAT ACCACTCACACCCTCCCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag34 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTACCGATCACCATACCCCTCGCC CCACAGCCCACAACATCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag35 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGACCAACATCTCACGCCCGCA CTCTCTAGCGCCCGCGAGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag36 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAGAGATCGAGATAACCAACaac agaccaacaacacacaatAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag37 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCACCCAAGCGAGCCCCCCAACA CGATCTATCCCACACTACAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag38 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTATCCCCAGCGAACTATAGATAA CGATCGACACATCCACCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag39 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCACCCCCTCTAACACGAACT CGACATCAAAATCACCCTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag40 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAAAGACACACCAACATATAACC CCAGAACCCTAGACCGACAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag41 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAGAGACACCCAACGACCTCGAG ACCACCACAGACCTCACGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag42 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCTCTACCACTAGCTCGATAT ACCCCTACCACCAGCTCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag43 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCGCTATACCTCTCCCGCCCT CAACCTAAACATCCAACAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag44 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAAATATATCCAACTACCGAGAC CCATCCCGCAACACATATAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag45 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGACCGCCCTACCGAACCATAC CTCCCACGAAACCACACAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag46 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTCACCCTCTCTCGCACCACCC CTATCCCGAGAACCCAACAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag47 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCACACAATAACTCAAGAAAT AAAACCCCCGCGAGCTCTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag48 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTCTAGACATAACTCCCACCCC AGACCCAAAAATCCCCCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag49 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCCCTCTCAAGACAACGACCT CAACCTACATCACAACCGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag50 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCAACGCGCCCACGATACATAC CCATCGACCCCGATCCCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag51 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTATCCCTACAAACAGACCGCACC ATCTCCCTCACGAAAACTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag52 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCAACGAGAAAGATCAAGACAG ATAACTCCCGCCAGATCGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag53 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTCTCGCTCCACAAACCCCACA CCCCCGAGAGCACCACCGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag54 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAAACCTCGCGCGAGAAAGAAAC AGATAGATATCACTCACAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag55 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCATCCACCTATAAAACGCAAC ATCCACAACACCCTCTCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag56 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCACTAGAAAAACCAAAACAACG CCATACACAACCACATCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag57 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAGCCAGCCAGCCCGATCAACAA CCATCACGCGCTATCGACAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag58 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCACCTAAACACACCCCCCTAA AGAAAGCAACCCACACAGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag59 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTATAAACAGCGCCCTACCCAACG AAAGACAACACTCACGCTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag60 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTACAGAACACTCTCTACCTCTCT AGCCACCACGAAAAATCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag61 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCAATCAACATAGCCCGACACAC CACGACACCACTCCCGCTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag62 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTAACCCCACACCTACCCCAATAA ATCTACACCACGCAAACGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag63 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCTCACCCCCGATACCACACC CCCAACATCGATACCTCCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag64 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGCCATCACACGATCCCGCCCC AACCACAACTCAATACAAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag65 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCACGATACCCCTAGACACCCCG AGCCCGCCCAATCTCCAAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag66 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCGCGCTCCCTCTAACCAACCAC ATCGATAAAACGACATCAAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag67 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCTCGAAAAACACACATCCACAT CGAGCTCTCTACACAGAGAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag68 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTCCCACTAGATAAACAACGACAG ACCGCTCCCCATAGATCTAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC tag69 GGTCTCTGAGATCCATACGCAGCTATGCAATAAGCTTACCTCCACAGACCTAGCTCGAC ATCCCACCATAAACAACCAAGCTTGTCATTGCTGTACCCCACAACACATGAGACC
* Grey highlighted sequences are tag specific.

pcwrA-rsaOV-F CTGCAGGTCGACTCTAGAGGTCAAATAAACCTTCGCCTATGC pcwrA-rsaOV-R CCATTCAGGCTGCGCAACTGAGTCAATCGTTGCGTTTTACTT pcwrA-F TTTCTTTTAAGTCACCTAAGACGACTTCTTTTATATAGATGCTAAGTAG pcwrA-R ATCTATATAAAAGAAGTCGTCTTAGGTGACTTAAAAGAAATCAGATGG pcwrA truncated -RsaOV-F TATAAAGGAGTATGATAGCGTGCGAAAGAATTTAACCCATCTGA pcwrA truncated -RsaOV-R ATGGGTTAAATTCTTTCGCACGCTATCATACTCCTTTATATTTCTCTT prsaOV-F TATAAAGGAGTATGATAGCGGTCACCTAAGAATTGCAAATCCAGA prsaOV-R ATTTGCAATTCTTAGGTGACCGCTATCATACTCCTTTATATTTCTCTT cwrA ATG  TAA UpF GAATTCGAGACCGCTAGCGCACGAACGACTTTACAAGGGT cwrA ATG  TAA UpR GTAATTAATATTCTTTACGCTATCATACTCC cwrA ATG  TAA DwF GCGTAAAGAATATTAATTACAGGCACA cwrA ATG  TAA DwR GATATCGGATCCGAGACCCTAGCTTTGCGTGACGTTTGAT
* Up and Dw refer to upstream and downstream loci of the referred gene, respectively. F and R indicate that concerned primers are in the Forward or Reverse orientation with respect to the chromosome annotation, respectively.

Adaptation to high osmolarity and oxidative conditions

High osmolarity condition was set up by adding NaCl (1.5M) to BHI medium. None of the mutants from the tagged sRNA-deletion set was significantly affected when grown to exponential phase in high osmolarity medium (Figure 5). However, when the culture set was grown to stationary phase, diluted in the same medium (Sampling 2), mutants teg147, rsaD and sau6528 were underrepresented and mutant sau6569 was accumulated (Figure 5). An oxidative condition was obtained by adding H 2 O 2 (0.1mM) to the medium.

Mutant rsaD was underrepresented in this condition (Figures 6). Two mutants rsaOV and ssrS were underrepresented, only when the population went through stationary phase (Figure 6).

Growth in RPMI and RPMI no-folate media

We investigated the effect of sRNA deletions on different culture media with our of tagged sRNA-deletion set. We used RPMI (Roswell Park Memorial Institute) medium which was originally used for human cell culture; it contains amino acids, vitamins, inorganic salts and glucose [START_REF] Moore | Culture of Normal Human Leukocytes[END_REF]). This medium is also be used to culture bacteria under iron-limited condition. In addition, the RPMI-derivative named RPMI no-folate medium which does not contain folic acid was also used.

None of the mutants had significant phenotype in exponential phase when grown in these two media (Figures

Anaerobic growth in BHI and RPMI media

S. aureus is a facultative anaerobe; hence we tested the effect of sRNAs under oxygen-limited conditions. These conditions were performed by growing bacteria in Falcon tube (50 mL) completely filled with BHI or RPMI medium.

No mutant had significant phenotype in exponential phase (Sampling 1) in anaerobic BHI and anaerobic RPMI media (Figures 9 & 10

Adaptation to iron depletion and human serum

To investigate iron-deficient effects on sRNA gene deletions, DIP (2,2′-Bipyridyl) (1.4mM) was added to BHI medium to chelate its iron. To mimic the infection process, the mix of mutant strains was grown in BHI medium containing human serum (10%). In Sampling 1, no mutant had significant phenotype in both conditions (Figures 11 & 12). However, when the population went through stationary phase (Sampling 2), mutants teg49 and rsaOV were overrepresented in iron-depleted medium and in human serum, respectively (Figures 11 & 12,lower histograms).

Growth competition experiments in mice

7-week-year-old BALB/c female mice were chosen for an animal model test. The mix of sRNA-deleted strains (6-7x10 7 CFU/500l) was injected in 10 mice and performed in duplicate. Unexpectedly, only 3 in the total 20 mice survived just after 24-hours post infection. Blood, spleen and kidney samples were collected only from 3 surviving mice while liver samples were collected from total 20 mice. All mutants were evenly represented in blood, spleen and liver samples (Figures 13,14,16 & 17) while in kidney samples, mutant rsaOV grew badly (Figure 15). The validation of these observations will require repeating these experiments with inoculums containing fewer bacteria. The sRNAs seem to indiscriminately affect all cellular functions and contribute to bacterial homeostasis [1]. Remarkably however, sRNA gene deletions frequently have no detectable phenotype in laboratory conditions.

A major challenge in assessing the physiological roles of bacterial sRNAs is to find their targets [2]. Although widely used, computational target finding methods based on hybrid prediction algorithms do not yet reliably discriminate true targets from non-targets. A typical experimental approach relies on coprecipitation of RNA and RNA binding proteins such as Hfq, an RNA chaperone catalyzing intermolecular RNA pairing [3]. However, Hfq is not ubiquitous and in certain phyla (e.g., Firmicutes) seems not to be required for general sRNA-based regulation [4]. We previously reported the identification of Escherichia coli sRNA targets using an sRNA as bait to capture its substrate within RNA extracts in the absence of RNAbinding proteins [5]. This method was accurate but limited by low sensitivity to the identification of abundant targets.

Staphylococcus aureus is a major opportunistic pathogen. Numerous trans-acting regulators, including regulatory RNAs, contribute to the coordinated expression of multiple virulence factors [6,7]. Although about 200 S. aureus sRNAs were identified, very few of their respective targets are known to date [4]. We present here a target capture protocol, named "Hybrid-trap-seq" that exploits deep sequencing and bioinformatics to greatly improve sensitivity and specificity for the identification of biologically meaningful sRNA-target pairs. Applied to four staphylococcal sRNAs, Hybrid-trap-seq revealed numerous new sRNA-targets and sRNA-regulated pathways, and allowed us to connect sRNAs to specific biological functions.

Results and Discussion

In vitro sRNA target identification by Hybrid-trap-seq. To identify sRNA targets, we assumed that biologically relevant sRNA-RNA intermolecular interactions could be isolated in vitro. As proof of concept, we chose four S. aureus regulatory RNAs: i) RNAIII as paradigm of staphylococcal regulatory RNAs [8] and ii) three sRNAs (RsaA, RsaE and RsaH) that were previously found to be expressed during specific growth phases [9,10].

Strain HG003 was used as a model for staphylococcal regulation studies [11].

Total RNAs were extracted from 16 different growth conditions, pooled together and sequenced by high-throughput technology (RNA-seq). The RNA pool covered most of the S. aureus transcriptome (Table S1). Synthetic RNAIII, RsaA, RsaE and RsaH sRNAs were produced, biotinylated, and fixed to streptavidin-associated magnetic beads; each streptavidin-biotinylated-sRNA complex was incubated with the pooled RNA mix following the same procedure that was used previously for the discovery of omp mRNAs-RseX sRNA interactions in E. coli [5]. After washing steps, RNAs bound to sRNAs were eluted (Figure 1). Recovered RNAs were converted to cDNAs and sequenced by RNA-seq. In each Hybrid-trap-seq dataset, analyses of mapped reads showed that 42 to 64% of all annotated genes were covered by at least ten reads (Table S1), indicating nonspecific binding to the sRNA-baits. To filter out background noise from putative sRNA targets, we performed a differential expression analysis between the four datasets using the DESeq software [12]. Transcription units accumulating significantly more reads in one dataset than in the others were classified in this way. This procedure identified 101, 23, 32 and 69 in vitro targets of RNAIII, RsaA, RsaE and RsaH, respectively (Figure 2 and Dataset S1). Among them were several known RNAIII and RsaE targets, indicating that the in vitro Hybrid-trap-seq procedure captures physiologically relevant RNA-RNA interactions.

sRNA-mRNA binding rules and seed motif prediction. We analyzed the potential interactions between sRNA-baits and their putative targets using IntaRNA [13]. RNAIII was not included in this analysis due to its complex structure comprising multiple RNA binding sites [14]. The 5' regions of putative targets showed significantly stronger base-pairing potential with their respective sRNA than 5' regions of random sets of S. aureus transcripts (Figure S1), indicating that Hybrid-trap-seq identifies a subset of RNAs with specific affinity to the bait sRNA.

Studies on Gram-negative bacteria suggested that sRNAs bind their target through a seed matching mechanism involving a short conserved sRNA region [15][16][17][18].

Similarly, in Gram-positive S. aureus, a UCCC sequence motif is present in the four sRNAs studied and is involved in target recognition in the case of RsaE [10].

The numerous target candidates produced by Hybrid-trap-seq provided the opportunity to assess seed binding potential on a quantitative basis. We found recurrent sequence motifs in each target set (Figure 3). The predominant motifs are akin to Shine Dalgarno (SD) sequences (Figure 3) and are indeed mainly located at the SD site. Strikingly, each motif had a complementary sequence in the corresponding sRNA that paired exactly to the most conserved positions of the motif (Figure 3). The anti-SD-like motifs in sRNAs are mostly single-stranded [10], hence accessible to base-pairing, and are located in evolutionary conserved regions (Figure S2). Altogether, four independent lines of evidence (motif enrichment, complementarity with sRNA, accessibility and conservation) lead us to make it very likely that RsaA, RsaE, and RsaH operate through a seed binding mechanism targeting SD-like regions. The degeneracy (hence variability) of target motifs contrasts with the high conservation in cognate sRNA regions (Figure S2) consistent with previous phylogenetic studies that showed higher conservation on the sRNA side of sRNA-mRNA complexes [19,20].

A question raised by the use of an SD-like seed region is how specific recognition can be achieved. SD-like motifs in RsaA and RsaE targets (GGAGnnnUUU and AAGGGG) differ from the canonical S. aureus SD motif (AAGGAG, Figure S3) in notable ways and these differences are matched by specific complementary bases in the sRNA. RsaA may achieve further recognition specificity through two additional pairing sites (Figure 2A), potentially creating a double or triple anchored interaction, often spanning the mRNA start codon. RsaE has two CCCCTT repeats that match two AAGGGG repeats present in five potential targets (Figure 2B).

Targets with such double seed contacts include mRNAs rocD, rocF and the sRNA RsaOG. RsaH targets a canonical SD consensus (UAAAGGAG); no further target motifs were detected that could improve binding specificity. However, frequent hybrid predictions outside the SD sequence (Figure 2C) suggest that a variety of additional anchor points can coexist with the major SD anchor. For the three RNAs analyzed, Hybrid-trap-seq thus enabled the identification of a major SD-like seed binding motif, which can be canonical or modified, and may be combined with additional binding sites.

In vivo assessment of putative sRNA-targets. Hybrid-target-seq experiments are equivalent to genome-wide RNA-RNA retardation assays, with the same caveat: Do putative targets uncovered in vitro correspond to real in vivo targets?

As many regulatory RNAs that act by base-pairing affect the stability of their targets, we considered that putative targets would be validated if their abundance varied with sRNA expression levels. To test this, the relative amount of putative RNA targets was determined and compared by qRT-PCR upon induction of their corresponding regulatory RNAs or in the absence of the sRNA gene. A short induction time (5 min), was chosen to monitor the primary effect of sRNA induction on its targets.

To determine the accuracy of the method without bias, we systematically tested the most enriched RNAs with each of the sRNAs. In view of the large number of putative targets trapped (23,32,69,and 101 for RsaA,RsaE,RsaH and RNAIII,respectively), we chose for further study the 40% most enriched RNAs with RsaA or RsaE, and the 20% most enriched with RNAIII or RsaH.

Among the 54 tested candidates, a total of 11 were up-regulated and 7 downregulated upon sRNA accumulation compared to the reference condition (Tables 1 andS2). An effect of sRNA gene deletions on putative targets was less frequently detectable; nevertheless four mRNAs were up-regulated and one down-regulated in sRNA gene deletion mutant strains as compared to the wild type strain (Table 1).

Altogether, 21 out of 54 RNAs (39%) selected based on the unique criteria of in vitro enrichment were affected for their stability in vivo. Pulse-expression approaches are powerful methods for limiting the noise due to indirect effects. For example, after a short induction of Salmonella enterica GcvB or of E. coli RyhB sRNAs, only ~1% of the transcriptome was altered [21,22]. The high proportion of qRT-PCR-validated candidates identified after a similarly short induction time indicates that Hybrid-target-seq is a powerful means of identifying biological sRNA targets. We also performed in vivo tests of additional putative identified targets of RNAIII and RsaH that are functionally related to already selected genes. Among the 14 RNAs tested, 6 were up regulated and 1 was down regulated upon sRNA induction (Tables 1 andS2). We also confirmed qRT-PCR results by Northern blot (Figure 4). As i) these RNAs were selected for their physical association with sRNAs and ii) their in vivo quantity was affected by the quantity of sRNAs, we conclude that they are direct sRNA targets. Taken together, 41% of sRNA targets predicted by Hybrid-trap-seq were confirmed in vivo.

mRNA down-regulation is expected to result in lower amounts of the corresponding protein. However, mRNA up-regulation by sRNAs should be interpreted cautiously, as pairing that prevents RNA degradation might inhibit translation by, for example, masking the ribosome binding site of targeted messengers. It is worth mentioning that for 10 out of 11 up-regulated mRNAs, an interaction site has been predicted by IntaRNA (Figure 3). Putative targets that remain constant in our test could also undergo sRNA-dependent translational controls; it is thus likely that among them, some are also true sRNA targets.

New targets for RNAIII including mRNAs involved in iron uptake. RNAIII is an atypical regulatory RNA because of its unusual long length (512-nts) and its expression of a small protein, the delta-hemolysin [23]. It contributes to the transition from host colonization to tissue destruction at high cell density by repressing early surface virulence factors and activating exotoxins [24]. RNAIII forms duplexes with rot, spa, lytM, coa, and SAOUHSC_1110 mRNAs, encoding the regulator of toxin Rot, protein A, the peptidoglycan hydrolase LytM, a coagulase and a fibrinogen binding protein, respectively [4]. As expected, known RNAIII targets, i.e., spa, coa and SAOUHSC_1110 mRNAs, were significantly enriched when RNAIII was used as bait as compared to the other baits (Dataset S1). rot mRNA was highly enriched with RNAIII, but also retained by RsaH. The effect of RNAIII was tested in vivo on 24 putative targets and on coa and SAOUHSC_1110 mRNAs. Quantities of known RNAIII targets were reduced upon 5 min of RNAIII induction, thus validating our approach. Among the putative new targets, six mRNAs were down-regulated and three were up-regulated (Tables 1 andS2). Thus, in addition to four known RNAIII substrates, nine new targets were discovered.

Protein A (SpA) and Sbi prevent bacterial opsonophagocytic killing by lymphocytes and may act synergistically to promote S. aureus escape from immune responses during the host colonization phase [6]. Spa mRNA is down-regulated by RNAIII. sbi mRNA is controlled by SprD, a virulence related sRNA [25]. We show here that RNAIII also targets sbi mRNA revealing a RNAIII-dependent coordinated downregulation of sbi and spa. While this work was in progress, an independent study reported that RNAIII targets sbi mRNA [26], thus providing independent validation of our Hybrid-trap-seq approach.

It was recently proposed that RpiRC, a sugar-responsive regulator indirectly downregulates RNAIII [27]. However, our results identify rpiRC as an RNAIII target, as i) RNAIII interacts with rpiRC mRNA (Dataset S1), whose levels are increased in vivo by RNAIII overproduction (Table 1). One explanation that would reconcile the previous and present results is that RNAIII/rpiRC mRNA duplex would lead to RNAIII degradation.

Iron is a determining factor during the infection process and host iron sequestration inhibits bacterial growth [28,29]. In S. aureus, iron capture is mediated by staphyloferrin A and B siderophores [30], which are imported via the HtsABC and SirABC systems respectively. In addition, S. aureus imports xenosiderophores via FhuD1, FhuD2 and FhuBG. All three transport systems require the integrity of the FhuC ATPase. Another iron reservoir is heme which is imported by the Isd system [30]. Trapped RNAIII targets were strikingly enriched in mRNAs expressing proteins involved in iron homeostasis: sirABC operon, fhuCB operon, fhuD2, htsA, fur (encoding the intracellular Fe 2+ -sensing regulator Fur), hemH (encoding a ferrochelatase), and two siderophore-related mRNAs, iucB and sstD (Dataset S1).

Among those tested in vivo, we confirmed that mRNAs expressing SirA, FhuD2, and FhuC were down-regulated upon RNAIII induction (Table 1). fur mRNA levels did not vary when RNAIII was overproduced (Table S2). However RNAIII-fur pairing predictions involve the fur SD, leaving open the possibility that RNAIII acts at the translational level (Figure S4). During the host colonization phase, S. aureus does not produce hemolysins and the main pathways of iron acquisition likely utilize siderophores. In contrast, at higher cell densities, RNAIII expression is induced, and S. aureus enters into a tissue destruction phase characterized by erythrocyte lysis and the massive release of heme likely provides the major iron source [24,28,29]. RNAIII down-regulation of S. aureus iron acquisition systems may optimize bacterial fitness by limiting iron uptake and thus preventing toxicity when extracellular stocks are high, and switching between systems as a function of the growth phase and iron availability.

Host cells generate toxic reactive oxygen species as part of the primary response to bacterial infection. The Mn-containing superoxide dismutase SodA mediates elimination of superoxide radicals and contributes to reducing iron toxicity [31]. We observed that the trapped sodA mRNA was down-regulated in vivo upon RNAIII accumulation, possibly in parallel with reduced iron uptake. Interestingly, the response regulator AgrA is redox sensitive and consequently oxidative stress represses RNAIII expression [32], thereby stabilizing sodA.

RsaA is involved in autolysin regulation. RsaA, a 142-nt sRNA, is detected in all growth phases but its quantity strongly increases in stationary phase [9,10].

Trapping of RsaA targets identified seven mRNAs involved in cell envelope biosynthesis among a total of 21 enriched mRNAs (Dataset S1). This group included four mRNAs expressing CHAP-domain containing proteins; CHAP is mainly associated with peptidoglycan hydrolysis [33]. Each of the four identified mRNAs is transcribed from a distinct transcription unit. The probability of randomly finding four mRNAs expressing CHAP proteins (there are 14 such genes in the HG003 genome), among the selected candidates by RsaA trapping is 2.8 x 10 -6 . This very low probability indicates a functional enrichment of RsaA targets. In addition, mgrA mRNA, which expresses a pleiotropic regulator affecting autolysis genes and repressing biofilm formation [34], was found in our screen.

Nine putative targets were tested for in vivo variation of abundance upon RsaA induction. mgrA and two mRNAs expressing CHAP proteins (SAOUHSC_02855 and SAOUHSC_2883) were significantly up-regulated upon RsaA accumulation. In addition, the amount of SAOUHSC_02576 autolysin mRNA was up-regulated when the rsaA gene was deleted (Table 1). These experiments confirm an RsaA-dependent post-transcriptional regulation of genes involved in peptidoglycan homeostasis metabolism, which may impact biofilm-and stress-related functions.

Measuring protein levels of the RsaA gene targets will be valuable for understanding the role of RsaA in bacterial physiology.

RsaE down-regulates arginine metabolism. RsaE is an astonishingly well conserved 93-nt sRNA found in the bacillales order. In S. aureus, it accumulates at the onset of stationary phase. RsaE affects expression of several genes involved in transport, folate metabolism and the Krebs cycle, and could contribute to S. aureus adaptation in stationary phase [9,10]. Among its previously reported targets, mRNAs corresponding to opp3 and opp4 operons were significantly enriched in the Hybrid-trap-seq experiment using RsaE as bait; others, however, expressing Krebs cycle and folate metabolism enzymes were not enriched. Twelve new RsaE putative targets were tested for their in vivo variation upon RsaE accumulation.

Among them, two RNAs (RsaOG and SAOUHSC_02836) were up-regulated, and three mRNAs (rocD, rocF and SAOUHSC_01138) were down-regulated by RsaE (Table 1). The arginase RocF and ornithine aminotransferase RocD enzymes perform adjacent metabolic steps that mediate forward and reverse reactions to shift between proline and arginine pools via the urea cycle [35]. Strikingly, the rocF and rocD genes, which are genetically unlinked, are both negatively regulated at the post-transcription level by RsaE. The urea cycle is directly linked to the Krebs cycle via fumarate released by the formation of arginine from argininosuccinate.

The newly identified trapped targets expand the metabolic pathway that is subject to coordinate negative regulation by RsaE.

RsaH contributes to lactate metabolism regulation.

RsaH is a 128-nt sRNA that accumulates specifically in pre-stationary phase [9]. Putative RsaH targets found by Hybrid-trap-seq were associated with anaerobic and fermentation metabolism, virulence or oxidative stress (Dataset S1). Among the 21 putative targets tested in vivo for their variation upon RsaH induction, five were significantly up-regulated, expressing ferritin and proteins of unknown function, and three were downregulated (Table 1). The two most down-regulated mRNAs correspond to genetically unlinked genes encoding L-lactate dehydrogenase (SAOUHSC_00206, ldhE) and lactate permease (SAOUHSC_02648, lctP). These two genes are also negatively controlled by the redox-sensing regulator of adaptation to anaerobic conditions Rex [36]. Our results indicate that RsaH affects a Rex-mediated regulation by directly down-regulating lactate metabolism and transport genes. The third down-regulated gene is isaB, which encodes a putative virulence factor implicated in immune evasion and is induced by acidity [37]. rot mRNA was highly enriched in the RsaH capture experiment (Dataset S1), while in vivo rsaH induction did not result in a significant change in its quantity (Table S2). Nevertheless, in silico analysis support specific highly stable interactions between RsaH and the 5'UTR of rot mRNA (Figure S4). This leads us to hypothesize that RsaH exerts translational control on Rot expression. Interestingly, the transition from aerobic to anaerobic growth reportedly induces expression of genes involved in lactate metabolism (ldh, lctP), and of isaB and rot [38]. Our results indicate that RsaH contributes to the coordinated regulation of these genes.

Conclusions.

We developed an experimental strategy to identify RNAs selectively retained by regulatory RNAs. As the first step is based on the selection of RNA-RNA interactions, the candidates should be considered as primary targets.

Compared to previous methods, the use of deep sequencing greatly improved the sensitivity of target identification. The problem of inherent high background noise was solved by performing differential analyses of several trapping experiments in parallel. This approach increased the specificity of target identification and allowed detection of low abundance targets, a usual difficulty of affinity-based selections.

Subsequent in vivo target validation gave supporting evidence that Hybrid-trap-seq efficiently identifies sRNA-mRNA partners.

The multiple targets identified for each sRNA provided valuable data for the identification of seed motifs. Computational analysis of mRNAs trapped by RsaA, RsaE and RsaH suggested a major binding mode based on multiple seed motifs, involving an SD or SD-like sequence plus other regions often spanning the start codon. Interestingly, the multiple seed binding mode evidenced for RsaA and RsaE may explain observed discrepancies between computational predictions and actual sRNA-target pairs. Of the 68 putative mRNA targets we further analyzed, 41% had their amounts modulated in vivo in response to changes in their corresponding regulatory sRNA. This is a remarkably high success rate compared to other attempts to identify sRNA targets [2]. The fraction of valid targets is likely higher, as sRNAs can exert translational control without affecting mRNA stability. Strikingly, a substantial subset of targets for each given sRNA was functionally related. Identification of these new targets revealed that RNAIII, RsaA, RsaE and RsaH down-regulate iron transport, autolysins, arginine/proline pathway, and lactate metabolism, respectively (Figure 5). Altogether, the Hybrid-trap-seq experiments presented here provided more staphylococcal sRNA targets than was obtained over many years of research. It should thus be a method of choice to decipher sRNAcontrolled regulatory networks.

Materials and Methods

A detailed description of the experimental procedures can be found in Supporting Information.

Bacterial strains and plasmids. In vivo experiments were performed with S. aureus HG003 strain grown in BHI rich media [11]. For gene names, we used NCTC8325 nomenclature. The rnaIII, rsaA, rsaE and rsaH genes were inactivated by replacing the gene by a short tag sequence (Table S3). The rnaIII, rsaA, rsaE and rsaH genes were cloned into pRMC2, under the control of an anhydrotetracycline (aTc) inducible promoter [39].

Total RNA extractions in various biological conditions. Total RNA samples were extracted from HG003 grown in different conditions: i) eight samples in rich medium at OD 600nm 0. 6, 1.8, 3.3, 4.5, 7.2, 9.8 and 12.8, and late stationary phase (24 hours), ii) seven samples under stress conditions (cold shock, heat shock, oxygen limitation, alkaline stress, oxidative stress, disulfide stress, iron-depleted condition and iii) one sample from colonies on BHI-agar plates.

Hybrid-trap-seq. The procedure is summarized in Figure 1 and a complete explanation is provided in Supporting Information.

Computational analysis of RNA-RNA hybrids. Input sequences were the complete sRNA sequence and, for each putative target, the region from the transcriptional start site (TSS) to 100 nucleotides past the start codon, or the entire transcript when non-coding. TSSs were defined from sequencing of total pooled RNA as described [40]. Coordinates of coding and non-coding relevant transcripts are provided (Table S4). Target RNA-sRNA interactions were predicted using the S4).

x/y ratios represent the number of sequences featuring the motif / number of sequences in the target set. Each motif is connected to its locations in target RNAs (colored boxes) and to its best complementary site in the sRNA.

Grey areas in targets correspond to regions of interaction with sRNA predicted by IntaRNA [13]. Relative amount of putative sRNA-targets in srna to WT strains.

2

Relative amount of putative sRNA-targets in srna pRMC2-sRNA strains 5 min after aTc addition (induced state) to before aTc addition (non-induced state).

Studied sRNAs are either RNAIII, RsaA, RsaE or RsaH. Numbers in bold indicate that the target is significantly modulated by the absence (column srna/WT) or accumulation (+aTc/-aTc) of the indicated sRNA. The indicated standard deviation is based on independent biological triplicates. Complete data are presented in Table S2.

SI Materials and Methods

Bacterial strains, plasmids and growth conditions. Experiments were performed using S. aureus RN4220 (for cloning purposes) and HG003 strains (1).

For gene names, we used NCTC8325 nomenclature retrieved from Genbank file CP00025.1, which is the sequenced HG003 parental strain. Engineered plasmids were constructed in E. coli DH5, transferred to RN4220 (a transformable strain with exogenous DNA) and subsequently to HG003. S. aureus strains were routinely grown in Brain Heart Infusion (BHI) broth at 37°C under vigorous agitation (180 rpm). DH5 was grown in Luria-Bertani (LB) broth at 37°C. Antibiotics were added to media as needed: ampicillin, chloramphenicol at 100 and 20 µg/ml for E.

coli; chloramphenicol and erythromycine at 20 µg/ml and 5 µg/ml for RN4220;

chloramphenicol and erythromycine at 20 µg/ml and 0.5 µg/ml for HG003, respectively.

HG003 derivatives that do not express RNAIII, RsaA, RsaE and RsaH were constructed by rnaIII, rsaA, rsaE and rsaH genes replacements with specific tag sequences using a replication thermosensitive plasmid pMAD ( 2) derivative (pMAD*), as described (3). In Brief, the pMAD* derivatives pMAD*rnaIII::tag47; pMAD*rsaA::tag1, pMAD*rsaE::tag45 and pMAD*rsaH::tag49, contained the tag sequences sandwiched between up-and downstream of sRNA gene sequences.

pMAD* derivatives were constructed by Gibson assembly method (4) (primers in Table S4). The integrity of inserted DNA sequences was verified by DNA sequencing. The detailed strategy will be published elsewhere.

pRMC2 contains the repA, repC, tetR genes and the xyl/tetO promoter (5). The pRMC2 derivative containing rnaIII, rsaA, rsaE, rsaH (named pRMC2-RNAIII, pRMC2-RsaA, pRMC2-RsaE, pRMC2-RsaH, respectively) were constructed as follows: DNA sequences of interest were amplified from HG003 genomic DNA by PCR, using the primers indicated (Table S4). The resulting products were assembled into the pRMC2 PCR-amplified vector using the method developed by Gibson (4). The integrity of inserted DNA sequences was verified by DNA sequencing. Expression of inserted sequences upon addition of anhydrotetracycline (aTc) at 1 mM to the media was confirmed by qRT-PCR.

Total RNA extractions in various biological conditions. Total RNA was isolated as previously described ( 6) except for cells lysis. Briefly, cultures were centrifuged;

the pellets were frozen in liquid nitrogen and stored at -80°C until RNA extraction. Twenty µg of each of the 16 total RNA extracts were pooled to obtain the combined RNA extracts sample used as prey during the Hybrid-trap-seq procedure. In parallel, 5 µg of this sample were processed using the MICROBExpress kit (Ambion, AM1905) as recommended by the suppliers, for large rRNAs removal and before Illumina high-throughput sequencing.

Hybrid-trap-seq procedure. Synthetic RNAs were generated using the T7 MEGAshortscript kit (Ambion) according to manufacturer's instructions. Briefly, the four sRNA genes under the control of the T7 RNA polymerase promoter were PCR amplified using specific oligonucleotides (Table S4). PCR-products were purified using clean-up gel extraction kit (Macherey-Nagel). In vitro transcription assays were performed at 37°C using 150 ng of DNA matrix. After 4 h of incubation, DNA was removed by treatment with 1 µl of TurboDNase I (Ambion) at 37°C during 15 min. Synthetic RNAs were phenol:chloroform extracted, isopropanol precipitated, the pellets were washed twice with 70 % ethanol then dried and resuspended in RNase-free water.

Synthetic RNAs were 3'-end biotinylated as previously described (7). Briefly, 50 µl of in vitro transcripts at ~5 µg/µl were mixed with 100 µl of potassium periodate 60 mM dissolved in NaAc 66 mM pH 4.8, then incubated 30 min at 20°C in the dark.

The oxidation reactions were stopped by adding 150 µl ethylene glycol:water mM, incubated at 55°C during 5 min, and then mixed with the sRNA-bound beads.

After 15 min at 45°C, then 15 min at room temperature, the unbound RNAs were removed by magnetic beads separation. The RNA-bound beads were washed twice with 100 µl of wash buffer (7 mM Tris-HCl pH 8, NaCl 0.17 M). For RNA elution, beads were successively resuspended in 100 µl then 200 µl of RNase-free water separated by incubation during 2 min at 55°C. The eluted RNA fractions were ethanol precipitated and the pellets were resuspended in 19 µl of RNase-free water. RNA samples were analyzed by capillary electrophoresis using RNA Nano chips (Agilent) before Illumina high throughput sequencing.

Illumina high-throughput sequencing: The 4 Hybrid-trap eluted samples and the rRNA depleted pooled RNA sample were used to generate five oriented libraries as described (8). Libraries were sequenced using Illumina Genome Analyzer IIx to generate single-end 40-nt reads.

Read mapping on the genomic sequence: Reads passing the quality filter and trimmed of the sequencing adapters were aligned to S. aureus NCTC8325 chromosome sequence (CP000253.1) using bowtie VN:0.12.7 ( 9), converted to BAM files using SAMtools (10) and visualized in the Artemis viewer (11) as described (8).

Counting reads in each genomic region: The files of each four Hybrid-trap-seq experiments containing reads mapping at unique positions on the reference genome and deprived from the reads corresponding to bait-sRNAs were processed to identify putative targets as following. A genome annotation GFF file was built by combining the 2892 annotated genes retrieved from Genbank file CP00025.1 and the unannotated regions putatively expressed including antisense regions (specified as asSAOUHSC_XXXX for complementary strand of the annotated gene named SAOUHSC_XXXX) and intergenic regions (specified as IGRXXX-YYY for intergenic region between nucleotides XXX and YYY on the forward strand;

ComplIGRXXX-YYY for intergenic region between nucleotides XXX to YYY on the backward strand). Read counts per gene were calculated for each dataset with HTSeq-count (http://www-huber.embl.de/users/anders/HTSeq) using the SAM file and this GFF file as the input.

Differential expression analysis:

To identify specific RNA targets of each sRNAbait, a differential expression analysis was performed using the DESeq software, an R Bioconductor package which was developed to test gene differential expressions between multiple experiments (12). For all expressed genes and each sRNA-bait, log2-fold changes were computed from normalized read number of condition A (defined by the sRNA of interest dataset) to normalized read number of condition B (defined by the three other sRNAs datasets). Genes were considered as putative sRNA targets if with a log2-fold change ≤ -1.58 (3 fold change on the linear scale). This threshold was chosen in light of known RNAIII targets (spa mRNA had a log2-fold change of -1.5). Read-enriched transcription units were defined using side-by-side read-enriched regions. As one mRNA can putatively be targeted by several sRNAs, we specifically looked for RNAs enriched into two out of four sRNA datasets and we found that rot mRNA is enriched with RNAIII and RsaH.

Computational analysis of RNA-RNA hybrids. Target RNA-sRNA interactions were predicted using the IntaRNA package ( 13), the scoring of which is based on hybridization free energy and accessibility of the interaction sites in both RNA molecules. We used IntaRNA V.1. S5). We sought consensus motifs in putative target sequences using the MEME suite V.4.9.0 ( 14), run locally with options -dna -minw 4 -maxw 10.

Input sequence fragments were the same as above, that is from TSS to ATG+100

or entire transcripts for non-coding RNAs. As we worked with small sequence datasets and degenerate motifs, we did not rely on the MEME motif E-values but instead sought the motifs with highest raw counts for each target family. To obtain the motif with highest counts, we compared MEME output obtained with parameters -mod anr or -mod zoops and retained any motif found in at least 25% of sequences. As no such motif was found in RsaH targets, we further used parameter -minsites 15, which yield a single motif present in 44 out of 69 sequences.

The standard SD motif (Fig. S4) was identified by MEME using as input the 1114 S. aureus sequences for which a TSS could be identified by the above protocol, again considering the sequence from TSS to 100 nucleotides past the start codon (first start codon in case of multicistronic loci).

Quantitative reverse transcriptase PCR (qRT-PCR) and northern blots.

Overnight cultures grown in BHI supplemented with chloramphenicol were diluted 1000-fold in the same medium at 37°C. At OD600=0.6, aTc (1 mM) was added to the medium and cultures were sampled at 5 min. Each condition cultures were done in triplicate. RNAs were prepared as described (15). qRT-PCR experiments were performed on a subset of putative targets for each sRNA. For RsaA and RsaE, all of the 40 % most enriched targets were tested (log2-fold change ≤ -2.3 and -3, respectively). For RNAIII and RsaH the criteria applied for selection were: i) all of the 20 % most enriched targets (log2-fold change ≤ -3 and -3.8 respectively)

and ii) manual analysis based on keeping genes that are functionally related to already selected genes (for RNAIII: fbp, sbi, fhuC, fhuD2, sarH1, saeR; for RsaH: isaB, ftnA, lctP, SAOUHSC_00681, rot, trxB, SAOUHSC_00067 and pgsA). Data were analyzed as described (16). The geometric mean of 4 genes (recA, gyrA, glyA and ftsZ) chosen among 13 was used to normalize the samples. Genes were considered as significantly affected by sRNA overexpression if the fold-change from + aTc to -aTc samples or WT to sRNA samples were ≥ 1.5 or ≤ 0. 67.

Northern blots were performed as described (17)(18)(19). Samples were separated by either PAGE or agarose gels and probed with 32 P-labeled PCR probes using the Megaprime DNA labeling system (GE Healthcare) (for primer used, Table S3).

Introduction

RNA steady-state is maintained by a balance between RNA synthesis and RNA degradation. Degradation involves ribonucleases (RNases), which also contribute to RNA processing leading to active transcripts. 1-3 Ribonuclease III (RNase III) is an important ubiquitous endonuclease that cleaves double-stranded RNA. 4 It is involved in mRNA decay and mRNA processing. A major role is its contribution to ribosomal RNA (rRNA) maturation. 5 However, this function is also performed by other ribonucleases, and RNase III is dispensable in some bacteria. 4 In Escherichia coli, RNase III regulates its own expression by a feedback mechanism involving cleavage of a stem-loop within its own mRNA. 6 RNase III also contributes to numerous post-transcriptional regulatory systems, via the degradation of internal structures or RNA duplexes that involve mRNA/regulatory RNA interactions. 7,8 Staphylococcus aureus is a Gram positive bacterium involved in hospital and community-acquired infections including endocarditis, pneumonia, osteomyelitis and skin infection. 9,10 In S. aureus, the rnc gene (encoding RNase III) was inactivated in several strains and reported not to affect growth in rich media. 11-13 However, the absence of RNase III affects expression of numerous virulence genes and strongly decreased S. aureus pathogenicity in a murine peritonitis model as compared to the parental strain. 13 RNAIII, a 514-nt regulatory RNA with 14 stem loop structures 14,15 associates by base-paring with targeted mRNAs related to virulence, thus affecting their translation and stability. 11,13,16 By degrading RNAIII targets, RNase III contributes to the irreversibility of regulatory processes. 11,16,17 The use of wild-type and mutated forms of RNase III to co-immunoprecipitate associated RNAs revealed numerous

RNase III substrates and its global role in gene regulation. 18 RNase III was also recently shown to eliminate pervasive transcription that occurs in S. aureus. 12 Despite its multiple roles, RNase III is not essential is some organisms, such as E.

coli, 19 Streptomyces coelicolor, 20 and Salmonella. 21 In Bacillus subtilis, RNase III was considered as essential; 22,23 recent experiments indicate that RNase III is required to eliminate toxins encoded by the type I toxin/antitoxin (TA) system. 22 In S. aureus, RNase III was considered as non-essential. However, we were unable to delete rnc strain in some strains, leading us to revisit this view. Here, we demonstrate that the presence of lysogenic phages containing a Type I TA system renders S.

aureus dependent on RNase III. In addition, rnc S. aureus strains are more susceptible to phage infection, indicating that RNase III provides a selective advantage against deleterious effects of foreign DNA containing Type I TA systems.

Results and Discussion

RNase III may be essential for S. aureus.

NCTC8325 (aka RN1

) is a clinical isolate from a corneal ulcer; this strain and its derivatives are often used for genetic studies. 24,25 However, the positive regulator of σ B (rsbU) and a transcriptional activator of protein A (tcaR) are inactive, such that NCTC8325 is deficient for σ B -dependent regulation and protein A expression. HG003 is a NCTC8325 derivative in which rsbU and tcaR were repaired, and is proposed as a model strain for staphylococcal regulation studies (Figure 1). 26 NCTC8325 was also cured of 3 resident phages (Φ11, Φ12 and Φ13) yielding NCTC8325-4 (named RN450), 24 and then subjected to chemical mutagenesis yielding RN4220. 27 The latter strain is used to uptake foreign DNA thanks to the inactivation of a restriction system. 28 Like its parental strain NCTC8325, RN4220 is rsbU and tcaR. Comparative sequence analysis between the two strains reveals four large-scale deletions and more than a hundred SNPs in RN4220. 29,30 To characterize the role of RNase III in post-transcriptional regulation, we intended to construct rnc deletions in HG003 and RN4220. In S. aureus, locus replacements are classically performed by two-step homologous recombination with integration and excision of a conditionally replicative plasmid at targeted loci. This excision step usually results in ~50% clones having the expected mutations. We used a replication thermosensitive plasmid pMAD derivative to delete the rnc gene. 31 A PCR test following the excision step indicated that rnc deletions in RN4220 were obtained at the expected frequency. However, surprisingly none of the fifty tested colonies from a selection on HG003 had an rnc deletion indicating a strong selective advantage to remain rnc + in this strain, but not in RN4220 (Figure 1).

RNase III was considered as non-essential since the rnc gene was inactivated in several strains and reportedly did not affect growth in laboratory conditions. 32 A S.

aureus Δrnc was constructed in RN6390. 11,16 This strain derives from NCTC8325-4 and has characteristics similar to those of RN4220. The above results suggested that an active σ B regulation and/or the presence of prophages could prevent establishment of the rnc deletion in HG003.

The alternative σ B is a S. aureus global regulator induced during stationary phase and upon various stress. 33 Because of the importance of σ B regulation, we first tested the potential role of rsbU in RNase III essentiality. Two NCTC8325 derivatives deferring with their rsbU allele were tested: NCTC8325-4 (rsbU) and SH1000 (rsbU + ) (Figure 1).

The rnc gene was successfully inactivated in both strains indicating that rsbU is not involved in RNase III essentiality. In agreement with this conclusion, a Δrnc mutant was reported in S. aureus 15981 12 and USA300; 34 these strains, not related to NCTC8325, are also rsbU + 35 . Successful inactivation of rnc in RN6390 and NCTC8325-4 also indicated that the nitrosoguanidine mutagenesis underwent by RN4220 was not a determining factor for RNase III essentiality.

NCTC8325-4 differs mainly from NCTC8325 by the absence of three prophages that were expelled after two UV treatments. In contrast to NCTC8325-4, we were unable to introduce Δrnc in NCTC8325. This result indicates that prophages are likely associated with RNase III essentiality in S. aureus. In agreement with this proposal, neither NCTC8325 derivatives nor S. aureus 15981, in which the rnc gene was deleted, possessed Φ11, Φ12 or Φ13.

A phage encoded toxin is deleterious for S. aureus in the absence of RNase III.

TA systems encode poisons and their corresponding antidotes. In Type I TA systems, the antitoxin is an RNA that associates with the mRNA encoding a toxin to prevent its translation or to stimulate its degradation. 36,37 Toxin and antitoxin are often expressed from opposite strands of a same DNA region; in these cases, the two transcripts are complementary and may form duplexes targeted by RNase III. We considered that RNase III essentiality in HG003 could be due to the presence of Type I TA systems carried by resident prophages. These putative systems were search by visual inspection of HG003 high-throughput RNA sequences aligned on a genome browser.

Five loci with significant transcription on both strands were identified within the three prophage sequences (Figure S1). We hypothesized that these loci could generate toxicity in the absence of RNase III. Four loci, SAOUHSC_01580 within the prophage Φ12, SAOUHSC_02016 to SAOUHSC_02018 within prophage Φ11 and SAOUHSC_02176 and SAOUHSC_02236 to SAOUHSC_02238 within Φ13, were cloned into shuttle vector pCN38 (Table 1). No clone was obtained with the fifth locus (SAOUHSC_02076 to SAOUHSC_02078 sequence), maybe due to expression of the toxin in E. coli. pCN38 and its derivatives obtained in E. coli were recovered to transform RN4220 and RN4220 Δrnc. After 12 hours, clones were obtained for all transformations except for pCN38 containing SAOUHSC_02018 (named pSAP-TA) into RN4220 Δrnc (Table 2). However, this latter transformation gave rise to small size translucent colonies after 18 hours, which displayed altered growth in liquid rich medium (Figure 2). These results suggest that the SAOUHSC_02018 locus is deleterious for S. aureus in the absence of RNase III. As RNase Y is a major

Staphylococcal RNase, 38 we also tested the transformation efficiency of pCN38 and its derivatives in its absence: no major difference was observed between RN4220 and its Δrny derivative (Table 2).

To rule out that the above finding results from a polar effect associated with Δrnc or mutations due to the inactivation procedure, we constructed RN4220 Δrnc derivative in with the rnc gene was introduced at an ectopic position, yielding RN4220 Δrnc ECTO::rnc + (cf. Material and Methods). The weak growth defect associated with Δrnc was alleviated in the presence of the rnc + ectopic copy indicating its ability to complement Δrnc (Figure 2). As expected, transformation of RN4220 Δrnc ECTO::rnc + with pSAP-TA did not lead to slow growing translucent colonies; we therefore concluded that the pSAP-TA phenotypes in RN4220 Δrnc were solely due to the absence of RNase III.

SAOUHSC_02018 encodes a putative small peptide of 50 amino acids with a possible small transmembrane domain. On the opposite strand an asRNA is transcribed, which likely prevents expression of SAOUHSC_02018 (Figure S1). This structure is reminiscent of Type I TA systems. SAOUHSC_2018 and its asRNA were accordingly renamed sapT and sapA for S. aureus phage encoded Toxin and Antitoxin, respectively (also see below). The sapT start codon of pSAP-TA was replaced by a stop codon yielding pSAP-T*A. This mutagenesis modified neither sapT/sapA RNA complementarity nor the transcriptional start sequence of sapA. In contrast to pSAP-TA, transformants of RN4220 and RN4220 Δrnc with pSAP-T*A were observed after 12 hours. The presence of pSAP-T*A did not affect RN4220 Δrnc growth (Figure 2). We concluded that the SAOUHSC_02018 locus toxicity in RN4220 Δrnc was associated with the presence of SapT.

RN4220 Δrnc pSAP-TA was grown in liquid with several rounds of dilution over about five days and plated on a rich medium. Fast-growing clones were observed and selected for further studies. Plasmids from four independently selected fast-growing clones were extracted and re-introduced into RN4220 Δrnc. Three of them did not have any mutation in the sapT/spaA genes and led to initial phenotype (i.e., slow growing translucent colonies); this result suggests that chromosomal mutations circumvent sapT/spaA associated toxicity. One extracted plasmid did not confer slow growth when re-introduced into RN4220 Δrnc; the identified mutation changed TGG to TAG resulting in the replacement of SapT W28 by a stop codon. This result supports the conclusion that SapT is a toxic protein expressed in the absence of rnc.

RNase III interferes with the Type I TA sapT/sapA expression.

As sapT mRNA and SapA are expressed from complementary strands, they likely form duplexes targeted by RNase III. We therefore asked whether the Δrnc deletion could affect the amounts and profiles of both RNAs. The putative sapT and sapA promoter sequences have canonical σ 70 promoter sequences (TTTACT -n=17 -TATAAT for SapT and TTGAAA -n=17 -TATTAT for SapA) and are likely recognized by the S.

aureus housekeeping factor σ A . 39 Indeed, Northern blotting experiments indicate that the antitoxin SapA is detected at all growth phases, and accumulates in stationary phase in both RN4220 and RN4220 Δrnc strains (Figure 3). In RN4220, probing for sapT mRNA reveals a band of about 200 nucleotides, but not in stationary phase, suggesting that sapT mRNA may disappear as a result of SapA accumulation. Probing for sapT mRNA in RN4220 Δrnc shows a drastically different profile as in RN4220: (i) several higher molecular weight bands were detected and (ii) the pattern remained similar in all growth phases (Figure 3). These experiments are interpreted as showing that the absence of RNase III results in an inability to degrade sapT mRNAs and therefore contributes to its toxicity.

RNase III contributes to S. aureus adaptation to phage infection.

The sapT gene is conserved in staphylococcal phages Φ11, SP6, SA12, SA13, Φ55, StauST398-5 and Φ80α. These phages belong to unrelated phage families from different serogroups and containing varied integrases. 40 SapT is also present within lysogenized phages of numerous S. aureus isolates including NCTC8325, Mu50 and USA300. The COL isolate has only one prophage devoid of sapT but the gene is present in the SaPI3 pathogenicity island, a mosaic sequence including phage DNA. 41 In some strains, the -35 box of sapT transcriptional promoter is TTTACT rather than TTGCTT, which may affect the level of the toxin. For all these sapT-containing strains, the amount of SapT has to remain low. Consequently, a main reason for RNase III maintenance might be to ensure protection against toxicity of incoming DNA carrying Type I TA systems. To test this hypothesis, two phages, Φ11 and Φ80α, which carry the sapT gene, and the COL phage, L54a, (devoid of sapT) were plated on different genetic backgrounds including HG003, RN4220 and RN4220 rnc, RN4220 rny and COL. The number of plaque forming units (PFUs) and plaque morphology were studied at 37°C. L54a did not form visible plaques when infecting COL and HG003. No significant difference was observed in terms of PFU for RN4220 and its mutants. For Ф11 and Ф80α, turbid plaques were obtained in a parental strain whereas clear plaques were observed in absence of RNase III (Figure 4). L54a phage spotted on RN4220 and its rnc derivative gave turbid plaques in both cases. These results show that the presence of RNase III contributes to improve S. aureus survival to phage infection in the case of phages containing type I TA systems.

Conclusion

Giving the role of RNase III in several crucial RNA processing, one could expect that rnc integrity would be required for cell survival. However, because other RNases can substitute for RNase III, rnc mutants were obtained in several bacterial species.

RNase III was considered essential in B. subtilis. 22,23 However, essentiality appears to be due to the presence of toxins that are controlled by antisense RNA mechanisms;

RNase III was needed to silence such toxins. 22 In the absence of toxins, B. subtilis rnc becomes dispensable. In contrast, RNase III was considered dispensable in S. aureus.

Here, we demonstrate that the absence of RNase III is deleterious in S. aureus strains carrying Type I TA systems. Our results allow the initial finding on the role of RNase III in B subtilis from Condon's lab to be generalized to other species. It was recently reported that rnc was inactivated by transposon mutagenesis in the HG003 genetic background; however, the strain used was a derivative in which the Φ11 prophage was specifically cured to prevent homologous recombination with the used transposon element. 42 Therefore, we can conclude that in the absence of Φ11, HG003 becomes permissive for rnc inactivation. We observed that a wild-type S. aureus strain was more resistant to phages containing Type I TA systems than its rnc isogenic derivative.

Consequently, the essential role of RNase III would not be to process endogenous

RNAs, but rather to ensure a defense system against incoming DNA, therefore providing a selective advantage against phage infections.

Material and methods

Bacterial strains, growth conditions and plasmids

Strains and plasmids used in this study are listed in Table 1. S. aureus and E. coli

DH5α were grown at 37°C with aeration in BHI and LB media, respectively. When necessary, antibiotics were used as follows: chloramphenicol (5 μg/ml) and erythromycin (0.5 μg/ml) for S. aureus; chloramphenicol (10 μg/ml) and amipicillin (100 μg/ml) for E. coli.

Primers are listed in Table S1.

Expression of cloned genes in S. aureus was obtained using pCN38 derivatives. 43 The pSite1 plasmid was constructed as follows; Phage site1 (Figure S1) was PCR-amplified from HG003 chromosomal DNA using primers Site1_F/Site1_R, pCN38 was PCRamplified using primers pCN38-lin_F/pCN38-lin_R. pSite1 was obtained by assembling the two PCR fragments as described. 44 pSAP-TA (pSite 2), pSite3 and pSite4 were constructed as per pSite1 except that sapTA, Site3 and Site4 were amplified using Site2_F/Site2_R, Site3_F/Site3_R, and Site4_F/Site4_R, respectively. pSAP-T*A is a plasmid in which the sapT start codon was replaced by a stop codon as follows. pSAP-TA was PCR-amplified using the mutagenic primers SapT-mutF/SapT-mutR, the PCR product was self-ligated by Gibson assembly. 44 Chromosomal allelic exchanges were performed using pMAD2-based plasmids.

pMAD2 is a pMAD 31 derivative that allows to use one-step cloning strategy with the Type IIS restriction enzyme BsaI. 45 pMAD2, designed for another purpose than the experiments described here, was constructed as follows: i) the unique pMAD BsaI site, within the bla gene, was removed and ii) two BsaI sites and additional unique restriction sites were introduced. pMAD2 was fully sequence (accession number pending). For construction and map, see Figure S2.

pMAD2-DErnc was constructed for the chromosomal deletion of rnc as follow. The upstream and downstream rnc sequences were PCR-amplified from HG003 chromosomal DNA using primers Rnc-upF/Rnc-upR and Rnc-dwF/ Rnc-dwR, respectively. pMAD2 was PCR-amplified using pMAD-F/pMAD-R primers. pMAD2-DErnc was obtained by assembling the three PCR fragments as described. 44 pMAD2-DErny was constructed for the chromosomal deletion of rny as follow. The upstream and downstream rny sequences were PCR-amplified from HG003

chromosomal DNA using primers Rny-upF/Rny-upR and Rny-dwF/ Rny-dwR, respectively. pMAD2 was PCR-amplified using pMAD-F/pMAD-R primers. pMAD-DErny contains a specific tag sequence to mark the rny deletion which was designed for another purpose than the experiments described here. The tag sequence was obtained by a PCR-amplification on pTAG44 using Tag-F/Tag-R primers. pMAD2-DErny was obtained by assembling the four PCR fragments as described. 44 We constructed pECTO, a plasmid derived from pMAD2 which can be used for any chromosomal gene ectopic complementation (Figure S3). This plasmid allows insertions between SAOUHSC_00278 and SAOUHSC_00279. This region was chosen because i) it is conserved across S. aureus species and ii) our deep-seq RNA data from samples grown in 16 conditions failed to detect any transcription (Figure S3).

pECTO contains two fragments of ca. 800 bp corresponding to the region encompassing SAOUHSC_00278 (chromosomal coordinates 293951-294750) amplified using primers pECTO_A_F/pECTO_A_R, and SAOUHSC_00279

(chromosomal coordinates 294754-295555) amplified using pECTO_C_F/pECTO_C_R, and in between, a E. coli rrn strong transcription terminator, amplified using pECTO_B_F/pECTO_B_R, to avoid possible transcriptional interference associated with inserted. These three amplicons were assembled with the linear pMAD2 plasmid backbone as described. 44 The ectopic zone was deposited on genbank (accession number pending).

Plasmids pMAD2 and pECTO are available for scientific community as Addgene plasmids 67682 and 67683, respectively (https://www.addgene.org/).

The complementation of rnc was performed by the chromosomal insertion of the rnc gene using pECTOrnc, constructed as followed. The rnc gene with its upstream regulatory region was PCR-amplified from HG003 chromosomal DNA using primers rnc -comp-F/rnc-comp-R. pECTO was PCR-amplified using primers pECTO-lin-F/pECTO-lin-R. pECTOrnc was obtained by assembling the two PCR fragments as described. 44

DNA manipulation

DNA extraction, purification of PCR products and plasmid extraction were done according manufacturer's instructions (Macherey-Nagel, Hoerdt, France) with an additional step for S. aureus: cells were incubated for 1 h at 37°C with the lysis solution containing lysostaphin (10 mg/ml) (Sigma-Aldrich, St. Louis, MO, USA). PCR amplifications were performed using Phusion DNA (for cloning) and DreamTaq (for construct verification) polymerases according supplier's recommendations (Life Technologies, Saint Aubin, France).

Gene replacement and functional complementation

The inactivation of rnc and rny, and the rnc ectopic chromosomal insertion were performed as described 31 using pMAD2-DErnc, pMAD2-DErny and pECTOrnc, respectively, with the following modification: plasmid integration steps were performed at 37°C instead of 42°C to avoid unwanted mutations that may arise at 42°C in the presence of erythromycin. 13

RNA extraction & Northern blot analysis

Total RNAs were extracted as described. 46 Northern blots were performed as described. 47,48 Samples were separated by PAGE gels and probed with γ 32 -P labeled oligonucleotides (Table S1). To decipher the role of RNase III in the regulation of SapA/sapT mRNA, samples were recovered at OD 600 0.4, 2, 4, 6 and in stationary phase.

Phage preparation and drop assay

The prophage L54a was induced by UV treatment and recovered from S. aureus COL as described. 49 Phages L54a, Ф11 and Ф80α were amplified on plates as follow. One ml of BHI [for Ф80α, MgSO 4 (12.5mM) was added to the medium] was mixed to 10 µl of an overnight culture of RN4220 and incubated 15 min at 37°C. Three ml of top agar were added and plated onto BHI plate. The day after, the top agar layer was recovered and 1ml of BHI broth and 100 of chloroform was added. The mixture was then centrifuged and 1 ml of supernatant was recovered. The titer of phage, expressed as PFU, was determined as previously described. 49 Lysis plaque turbidity was observed after 8 and 16 hours and PFU were counted after 16 hours.

Disclosure of Potential Conflicts of Interest

Authors declare no potential conflicts of interest. 4 . pMAD2 contains two BsaI sites and additional unique restriction sites. When pMAD2 is digested by BsaI, the two BsaI sites do not remain associated with the vector and two cohesive non-complementary overhang sequences compatible with BamHI and EcoRI cloning sites are created. pMAD2 allows to clone multiple fragments using solely BsaI with properly designed PCR products. 4 (A) pMAD2 was constructed as follow: i) an unwanted BsaI site in the pMAD bla gene was removed; the resulting plasmid was named pMAD*. ii) a cloning site generating two cohesive noncomplementary overhang sequences upon BsaI digestion was created; the resulting plasmid was named pMAD2. To remove the BsaI site from pMAD, we used the property that BsaI does not cut within its recognition site, which allowed to exclude the BsaI site from a pMAD reconstructed plasmid. We amplified a part of the bla gene using the mutagenic primer (BsaImut) introducing a codon change GGG to GGA (gly to gly). This primer contained a BsaI site that generates a cohesive end compatible with the BsaI pMAD generated end. The second primer (upScaI) primed downstream a ScaI site. The PCR amplification using the two primers BsaImut/upScaI and pMAD generated a fragment of 500 bp. This PCR product and pMAD were ScaI digested and then ligated together leading a linear fragment, which was subsequently incubated with BsaI and the T4 DNA ligase together. The ligation mix was used to transform DH5αZ1. The presence of the expected mutation in the resulting pMAD* was confirmed by DNA sequencing. To construct pMAD2, two complementary oligonuclotides (except at their 5' ends) (BNNAXB / BNNAXB-as) were assembled together to generate a double stranded DNA as described. 5 The none-complementary 3' ends generated cohesive ends were compatible with BamHI and EcoRI sites, respectively. The assemble fragment (containing the two BsaI sites) was inserted between the pMAD* BamHI and EcoRI restriction sites giving rise to pMAD2. pMAD2 was fully sequence (accession number pending). (B) pMAD2 multicloning site sequence. Above the sequence, unique pMAD2 restriction sites are indicated. The two BsaI recognition sites are highlighted in yellow; the remove sequence upon BsaI digestion is underlined, and plasmid cohesive ends compatible with EcoRI and BamHI are highlighted in green and blue, respectively.

Acid and alkaline adaptation

In acidic condition, mutant sau6428 grew badly and mutant sau30 disappeared from the mutant set. In addition, both mutants also had growth defects at 42 o C (see chapter A.1).

Sau30 (Abu-Qatouseh et al. 2010) was also reported as a regulatory RNA under SSR154 name [START_REF] Anderson | Characterizing the Effects of Inorganic Acid and Alkaline Shock on the Staphylococcus Aureus Transcriptome and Messenger RNA Turnover[END_REF]). The gene is located between SAOUHSC_02483

(cbiO -cobalt transporter ATP-binding subunit) and SAOUHSC_02484 (rplQ -50S ribosomal protein L17). In HG003, our transcriptome data indicates that Sau30 is probably a part the rplQ 3'UTR rather that a sRNA per se and indeed, the rplQ gene is downregulated in acid-shocked cells [START_REF] Anderson | Characterizing the Effects of Inorganic Acid and Alkaline Shock on the Staphylococcus Aureus Transcriptome and Messenger RNA Turnover[END_REF]. The constructed sau30 deletion encompasses a large region that could also affect cbiO gene. Therefore, the two phenotypes observed at 42 o C and in acidic pH could be link to rplQ and/or cbiO.

Sau6428 (Abu-Qatouseh et al. 2010) also known as Teg109 [START_REF] Beaume | Cartography of Methicillin-Resistant S. Aureus Transcripts: Detection, Orientation and Temporal Expression during Growth Phase and Stress Conditions[END_REF] was initially classified as a sRNA located between SAOUHSC_00775 (hypothetical protein) and SAOUHSC_00776 (uvrB -excinuclease ABC subunit B). However, Sau6428 is likely the 5'UTR of uvrB mRNA (http://srd.genouest.org). UvrB is involved in nucleotide excision repair, a mechanism to repair DNA damage which is enhance by enviromental stress such as acidic growth media (see chapter II. 1.4.1) or heat shock.

The phenotypes observed for mutant sau6428 are possibly related to the altered expression of uvrB.

Only mutant sau6836 was underrepresented in alkaline condition. The sau6836 gene is located between SAOUHSC_00646 (penicillin binding protein 4, pbpD) and SAOUHSC_00647. Sau6836 initially consider as a sRNA is now categorized as a putative 5'UTR of SAOUHSC_00647 (http://srd.genouest.org). The abcA gene encoding an ABC transporter component is the SAOUHSC_00647 homolog in strain KB400. Its disruption was shown to increase resistance to cefoxitin and methicillin [START_REF] Domanski | Analysis of Staphylococcus Aureus Genes Encoding Penicillin-Binding Protein 4 and an ABC-Type Transporter[END_REF]. This phenotype was later proved to be due to phpD upregulation, resulting in increased peptidoglycan crosslink in S. aureus cell wall [START_REF] Domanski | Transcription Analysis of the Staphylococcus Aureus Gene Encoding Penicillin-Binding Protein 4[END_REF]. abcA and pbpD share an overlapping 80 nt promoter region and are controlled by common regulatory mechanism. However, abcA and pbpD expressions are different in strain NCTC8325 [START_REF] Schrader-Fischer | The AbcA Transporter of Staphylococcus Aureus Affects Cell Autolysis[END_REF]. abcA is regulated by the Agr TCS, expressed from a pathogenicity island [START_REF] Beaume | Cartography of Methicillin-Resistant S. Aureus Transcripts: Detection, Orientation and Temporal Expression during Growth Phase and Stress Conditions[END_REF]. Its gene is located between SAOUHSC_00380 (hypothetical protein) and SAOUHSC_00381 (hypothetical protein). So far, the growth defect in high osmolarity condition is the first reported phenotype for mutant teg147.

The third deletion mutant, sau6528, grew badly at 20 o C (see Chapter A.1) and in high osmolarity conditions. Sau6528 likely affects the 3'UTR of SAOUHSC_01416 (odhB) gene encoding a dihydrolipoamide succinyltransferase converting the 2oxoglutarate to succinyl-CoA in the TCA cycle. odhB is upregulated under biofilm condition [START_REF] Resch | Differential Gene Expression Profiling of Staphylococcus Aureus Cultivated under Biofilm and Planktonic Conditions[END_REF]. Biofilms protects bacteria better from harsh environments including to high osmolarity. Consequently, high concentration of NaCl induce or increase biofilm formation [START_REF] Lim | Control of Glucose-and NaCl-Induced Biofilm Formation by Rbf in Staphylococcus Aureus[END_REF][START_REF] Rachid | Alternative Transcription Factor Sigma B Is Involved in Regulation of Biofilm Expression in a Staphylococcus Aureus Mucosal Isolate[END_REF].We suggest that Sau6528, as a 3'UTR, contributes to odhB gene expression.

Resistance to oxidative stress is crucial for bacteria to survive within infected hosts which produce toxic reactive oxygen species (ROS) such as hydrogen peroxide, superoxide and hydroxyl radicals. These ROSs damage DNA, proteins, and other cellular macromolecules. Therefore, all bacteria developed several mechanisms to response to oxidative stress. For example, S. aureus produces catalases and superoxide dismutases to degrade hydrogen peroxide and to prevent ROS-associated damages. In oxidative growth condition, ssrS, rsaD and rsaOV mutants grew badly suggesting that the deleted sRNAs may contribute to the expression of ROS protecting enzymes.

The ssrS gene is conserved in bacteria. It expresses the 6S RNA that associates with  70 RNA polymerase. Interestingly, many genes directly related to oxidative stress adaptation such as degradation of superoxide and hydroperoxide are upregulated in the B. subtilis ssrS mutant [START_REF] Hoch | Phenotypic Characterization and Complementation Analysis of Bacillus Subtilis 6S RNA Single and Double Deletion Mutants[END_REF]. In Burkholderia cenocepacia, 6S RNA was shown to increase during oxidative stress [START_REF] Peeters | Transcriptional Response of Burkholderia Cenocepacia J2315 Sessile Cells to Treatments with High Doses of Hydrogen Peroxide and Sodium Hypochlorite[END_REF]. These results indicate that 6S RNA is related to oxidative stress and support our observation that S. aureus 6S

RNA is required for a better growth in media containing H 2 O 2 .

Mutant rsaD had a growth defect at 20 o C (see Chapter A.1), in high osmolarity and in oxidative conditions. Noticeably, RsaD is induced in cold shock and oxidative stress by H 2 O 2 [START_REF] Beaume | Cartography of Methicillin-Resistant S. Aureus Transcripts: Detection, Orientation and Temporal Expression during Growth Phase and Stress Conditions[END_REF]Geissmann et al. 2009). This induction may reflect that RsaD contributes to adaptation to cold and oxidative stress and explains the defective growth of the rsaD mutant in low temperature and in media containing H 2 O 2 .

It contributes to validate our method for identifying sRNA functions by performing fitness experiments.

Adaptation to RPMI and RPMI no-folate media

Mutant rsaH grew badly in RPMI medium while mutant sau6836 was underrepresented in RPMI no-folate and completely disappeared in RPMI.

Mutant rsaH also had growth defect at 42 o C (see chapter A.1). Putative RsaH targets were found to be involved in lactate metabolism, virulence and oxidative stress (see chapter B). However, we have not found yet links between rsaH mutant phenotypes and RsaH putative targets.

Mutant sau6836 grew badly at 42 o C (see Chapter A.1), alkaline pH and RPMI (with and without folate). As discussed before, Sau6836 is likely the 5'UTR of SAOUHSC_00647, the observed phenotypes are probably due to an altered expression of abcA encoded TCS component (see Figure 20). In addition, the abcA mRNA is strongly induced under nutrient limitation condition [START_REF] Villet | Regulation of Expression of abcA and Its Response to Environmental Conditions[END_REF]) as it may be required for this condition. It could explain the growth defect of mutant sau6836 in poor medium

In RPMI no-folate medium, we expected to see a phenotype of mutant rsaE since RsaE was shown to be involve in TCA and folate metabolism (Bohn et al. 2010), however, no growth phenotype was observed in RPMI and RPMI no-folate.

Growth in anaerobic BHI and RPMI media

We found mutant sau30 was under-represented while mutant teg49 accumulated in the mutant set growing anaerobicaly. As discussed before, the phenotype of mutant sau30 can be due to an altered expression of its flanking gene.

The teg49 gene is located between SAOUHSC_00620 (sarA, encoding the accessory regulator A) and SAOUHSC_006201. Recently, it was demonstrated that Teg49 correspond to the 5'UTR of sarA transcribed from the sarA P3 promoter, hence

Teg49 also modulate sarA expression [START_REF] Kim | Contribution of teg49 sRNA in the 5'-Upstream Transcriptional Region of sarA to 2 Virulence in Staphylococcus Aureus[END_REF]. Consequently, the deleted region of our mutant teg49 also affects sarA expression; the accumulation of mutant teg49 in anaerobic RPMI medium could due to the loss of sarA function. This is the only mutant strains that accumulated significantly in our fitness experiments.

Adaptation to iron limitation, human serum and in mouse model

In iron limited condition, we did not obtain any significant phenotype but mutant teg49 was the most overrepresented strain of the mutant set. It is consistent with the accumulation of this mutant in anaerobic RPMI medium which are also iron limited. In addition, we expected to observe a growth phenotype associated with mutant RNAIII/agrB as we found new putative RNAIII targets that are involved in iron uptake (see Chapter B). However, no RNAIII associated phenotypes were observed in these media (Figures 19 & 20). Nevertheless, a weak growth defect of mutant RNAIII was found in TSM (Trichoderma-selective medium) containing the iron chelator EDDHA (ethylenediamine-N,N'-bis (2-hydroxyphenylacetic acid) in the final concentration 1µM

(Tatiana Rochat, unpublished data). The absence of phenotype for the competition experiment could be due to a specific condition associated with the iron chelator that we used.

rsaOV (Sau40) is the 3'UTR of cwrA. In addition to a growth defect in media containing H 2 O 2 , mutant rsaOV had a strong growth defect at low temperature (see Chapter A.1). Importantly, this mutant was also underrepresented in kidney in our mouse model. Our results are consistent with the observation that cwrA expression in strain SH1000 is required for S. aureus virulence in mouse sepsis model (Balibar et al. 2010). These data suggested the role of rsaOV acting as 3'UTR in regulating cwrA gene expression, leading to pleiotropic effects in adaptation and virulence.

RNAIII and SprD are well-characterized sRNAs in S. aureus. sprD is required for bacterial virulence in a mouse infection model [START_REF] Pichon | Small RNA Genes Expressed from Staphylococcus Aureus Genomic and Pathogenicity Islands with Specific Expression among Pathogenic Strains[END_REF]Chabelskaya et al. 2010) (see Chapter IV.3). However, we did not obtain any phenotype of mutant RNAIII/agrB or mutant sprD in any fitness experiment, including the mouse model. This latter negative result could be attributed the high toxicity of the inoculum that we used which consequently reduced the number of mice that we analysed and also shorten the competition time. As indicated before, this experiment should be performed again with a larger sample and less toxicity inoculum.

Identification of sRNA targets in S. aureus

To understand how sRNAs are related to their phenotypes, it is important to identify sRNAs targets and determine the mechanism of sRNAs action. Several computational methods proposed a list of putative sRNA targets. However, it is often difficult the find the right target within a long list of candidates. Therefore, we developed the strategy inspired from (Douchin et al. 2006), named "Hybrid-trap-seq" to identify reliably sRNA targets. We performed in parallel hybrid-trap-seqs to four S.

aureus sRNAs RsaA, RsaE, RsaH and RNAIII. Many known sRNA-targets as well as new ones were revealed and confirmed (see chapter B). However, there is still a gap between hybrid-trap-seq targets and our fitness phenotypes. We did not obtain any phenotype for mutant rsaA, rsaE and rnaIII in the specific condition that these mutants supposed to have effects, such as folate-limited medium for rsaE or iron-limited medium for rnaIII. Further experiments are needed find deficiencies associated with these deletions.

Difficulties

The pMAD plasmid is a tool classically used for disruption gene in S. aureus (Arnaud et al. 2004). However, it was shown that the integration step at 42 o C of pMAD generates secondary mutations in the sae operon during the process [ [START_REF] Sun | Aureusimines in Staphylococcus Aureus Are Not Involved in Virulence[END_REF],

our data]. It is likely that the growth at high temperature in presence of erythromycin generates mutations in other genes. When we became aware of this problem, we change the allelic exchanged protocol by performing the integration step at 37°C instead of 42°C. To minimize the effect of secondary mutations associated with the allelic exchange protocol, we propose to associate each deletion with 2 or 3 different barcodes; consequently each mutant will be independent and will not have the same potential secondary mutations. The different tag versions of each deletion mutant will provide an internal control to confirm that the observed phenotypes are directly related to deletions.

We constructed a set of 39 sRNA genes substituted with specific DNA tag sequences in the pathogenic strain HG003. The regions chosen for the sRNA gene disruptions were based on data evaluable at the beginning of the project. As described before, the cartography of the sRNA genes was incomplete and several reported sRNAs correspond in fact to mRNA UTRs. Hence, few constructed sRNA mutants have an effect on the flanking genes rather than on the sRNA gene itself.

A resource for Staphylococcal regulatory RNAs Database (SRD http://srd.genouest.org/) providing a list of curated sRNAs in S. aureus was recently created [START_REF] Sassi | SRD : A Staphylococcus Regulatory RNA Database[END_REF]. This resource combined with our transcriptome of strain HG003 grown in 13 different conditions allow a more accurate knowledge of HG003 sRNAs than 4 years ago. The data set presented in this work could in the future i) be corrected with adequate deletions and ii) be extended with new sRNA gene deletions.

Competitive fitness experiments

Since antibiotic resistance in S. aureus is a major problem, one of the most promising experiments will be to perform fitness experiments with a complete sRNA mutant set growing in the presence of sub-lethal concentration of different antibiotics.

409 putative regulatory RNAs were identified in strain multiresistant sequence type 239 (ST239) after it was exposed to 4 antibiotics vancomycin, linezoid, ceftobiprole and tigercycline [START_REF] Howden | Analysis of the Small RNA Transcriptional Response in Multidrug-Resistant Staphylococcus Aureus after Antimicrobial Exposure[END_REF]). Other antibiotics using for S. aureus treatment such as glycopeptides, 'late-generation' cephalosporins, fluoroquinolones, aminoglycosides, oxazolidinones and macrolides can be tested. Importantly, sRNAs contributing to the pathogenicity of S. aureus can also be identified by performing competition experiments within macrophages or animal models. These results could help us to understand the functionality of sRNAs related to antibiotic resistance and virulence and to decipher parts of the S. aureus regulatory network controlled by sRNAs.

Figure 1 :

 1 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 2 :

 2 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 3 :

 3 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 4 :

 4 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 5 :

 5 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 6 :

 6 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 7 :

 7 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 8 :

 8 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 9 :

 9 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 10 :

 10 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 11 :

 11 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 12 :

 12 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 13 :

 13 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 14 :

 14 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 15 :

 15 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 16 :

 16 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 17 :

 17 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 18 :

 18 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 19 :

 19 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 20 :

 20 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 21 :

 21 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 22 :

 22 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 23 :

 23 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 24 :

 24 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 25 :

 25 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 26 :

 26 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 27 :

 27 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 28 :

 28 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 29 :

 29 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 30 :

 30 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 31 :

 31 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 32 :

 32 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 33 :

 33 Figure 1: Staphylococcus aureus also known "the golden Staph". ..........................................Figure 2: Sites of infection and diseases caused by S. aureus. ................................................Figure 3: Model of SrrAB system. ............................................................................................Figure 4: Model for the NreBC sensor and regulation system in staphylococci. ....................Figure 5: The CtsR, HrcA regulon of S. aureus......................................................................... Figure 6: Mechanism of acid resistance of Gram-positive bacteria ........................................Figure 7: Human lines of defense against pathogens ..............................................................Figure 8: Mechanisms by which S. aureus subverts host innate immune defense .................Figure 9: Scheme of a competitive fitness assay. ....................................................................Figure 10: Signature-tagged mutagenesis in Salmonella. ........................................................Figure 11: Example of cis-encoded antisense RNAs (asRNAs). ................................................Figure 12: Antisense regulation of plasmid pT181 replication. ...............................................Figure 13: Gene arrangement and regulatory functions of sRNAs. .........................................Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. ........................................................................................................Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. ................Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control ........Figure 17: RNA polymerase interacts with 6S sRNA in E.coli ...................................................Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus .............Figure 19: Regulatory circuits involved in virulence gene expression .....................................Figure 20: RsaE controls metabolic pathways. ........................................................................Figure 21: RsaA and its regulatory circuits. ..............................................................................Figure 22: Base-pair association of SprD with sbi mRNA. ........................................................Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains. ...................Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. ...........Figure 25: Examples of RNase III functions. .............................................................................Figure 26: Schematic representation of the saePQRS operon ................................................Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y and PNPase.. ..................................................................................................................................................Figure 28: Regulatory mechanism of FasX with the ska mRNA. ..............................................Figure 29: Examples of regulatory RNAs in Clostridium. .........................................................Figure 30: Regulatory mechanism of LhrA and chiA mRNA. ....................................................Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. ...................................................................................................................Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. ....................................Figure 33: Riboswitch-based regulation. ................................................................................ Table 1: Summary of experimentally validated regulatory RNAs in S. aureus ........................ Table 2: Ribonucleases in S. aureus .........................................................................................

Figure 1 :

 1 Figure 1: Staphylococcus aureus also known "the golden Staph".

Figure 2 :

 2 Figure 2: Sites of infection and diseases caused by S. aureus.

Figure 3 :

 3 Figure 3: Model of SrrAB system. PIA: Polysaccharide intercellular adhesin production.

Figure 4 :

 4 Figure 4: Model for the NreBC sensor and regulation system in staphylococci.

Figure 5 :

 5 Figure 5: The CtsR, HrcA regulon of S. aureus

Figure 6 :

 6 Figure 6: Mechanism of acid resistance of Gram-positive bacteria [Adapted from (Cotter & Hill 2003)]. During its life cycle, S. aureus can undergo various pH conditions within or outside the host. It can survive in human body, colonize and cause infection in different places which have acidic to alkaline pH such as external labia (pH 3.8 -4.5), lysosomal compartments (pH 4.5 -5.5) and wound sites (pH 8.9).

Figure 7 :

 7 Figure 7: Human lines of defense against pathogens http://www2.bakersfieldcollege.edu/bio16/15_innate_immune.htm S. aureus developed different mechanisms to evade the innate immune system by inhibiting phagocyte functions, blocking complement activation, resisting antimicrobial peptides, lysing neutrophils (Nizet 2007) (Figure 8).

Figure 8 :

 8 Figure 8: Mechanisms by which S. aureus subverts host innate immune defense. Phagocyte recruitment is limited by binding of CHIPS (Chemotaxis inhibitory protein of Staphylococcus aureus) to chemokine receptors. Complement activation is blocked by protein Efb binding of soluble C3 and inhibition of the both the classic/lectin and alternative C3 convertases by SCIN (Staphylococcal complement inhibitor).Golden carotenoid pigment provides an antioxidant shield whereas catalase detoxifies hydrogen peroxide.Resistance to cationic antimicrobial peptides is afforded by positive charge modifications of the cell wall, aureolysin-mediated proteolysis, and binding/inactivation by staphylokinase. Protein A binds Fc domains of Igs in a nonopsonic manner, whereas fibrinogen binding clumping factor and the surface polysaccharide capsule and poly-N-acetylglucosamine (PNAG) act to cloak surface bound opsonins from phagocyte recognition. The heptameric pore-forming toxins -hemolysin and Panton-Valentine leukocidin (PVL) preferentially target leukocyte membranes. The plasminogen (PG) binding protein staphylokinase (SAK) activates the zymogen to the active protease plasmin, which can degrade complement opsonin C3b and the immunoglobulin Fc domain [From[START_REF] Nizet | Understanding How Leading Bacterial Pathogens Subvert Innate Immunity to Reveal Novel Therapeutic Targets[END_REF]].

Figure 10 :

 10 Figure 10: Signature-tagged mutagenesis in Salmonella. A) Design of a signature tag. Each tag has a unique central sequence of 40 bp ([NK] 20; N = A, C, G, or T; K = G or T), flanked by invariable arms of 20 bp, which are common to all the tags. B) Signature-tagged mutagenesis screening in mice. A complex pool of tags (shown as colored rectangles) is ligated to transposons. The tagged transposons are then used to mutagenize bacteria, which are subsequently assembled into a library. Only bacteria with tags that are efficiently amplified by PCR and are not cross reactive with other tags in hybridization experiments are selected for inclusion in the

(

  often 75 nucleotides or more) with which they fully or partially overlap to activate or inhibit mRNA functions (Waters & Storz 2009; Georg & Hess 2011) (Figure 11). Most studied asRNAs are from bacteriophages, plasmids, and transposons and control phage development, plasmid replication and copy-number control of mobile elements, respectively.

Figure 11 :

 11 Figure 11: Example of cis-encoded antisense RNAs (asRNAs). mRNAs in blue, asRNAs in red.

Figure 12 :

 12 Figure 12: Antisense regulation of plasmid pT181 replication. (A) Genetic organization of pT181 plasmid and its control region. RNAI and RNAII are asRNAs. (B) Schematic secondary structure model of repC mRNA leader region as proposed by (Novick et al. 1989). The formation of a large helical domain formed by helices I and III favors the formation of an anti-terminator hairpin that stimulates the transcription of the complete mRNA. In this structure, the Shine and Dalgarno sequence (SD) and the initiation codon are available for translation. (C) The antisense RNAI traps a transient hairpin structure of repC mRNA during transcription, and the formation of the RNAI-mRNA duplex stabilizes a Rho-independent terminator to arrest transcription.

Figure 13 :

 13 Figure 13: Gene arrangement and regulatory functions of sRNAs. Genes encoding trans-encoded sRNAs (red) are located separately from the genes encoding their target RNAs (blue) sRNAs have a limited base-pair complementarity with their targets. (Left panel) sRNAs can base pairing to 5'UTRs and block ribosome-binding site (RBS) and/or (Middle panel) target the mRNAs to degradation by ribonuclease. (Right

Figure 14 :

 14 Figure 14: C-rich box conserved motif in S. aureus sRNAs and an example of example sRNA/mRNA base pairing. (A) Alignment of the C-rich sequence motifs of S. aureus sRNAs [From (Geissmann et al. 2009)]. (B) Repression of mgrA mRNA translation by the sRNA RsaA. Two regions of RsaA base pair i) with the mgrA mRNA RBS and ii) with the coding region via a loop-loop interaction. The two regions are essential to repress translation and to enhance the mgrA mRNA degradation [From[START_REF] Fechter | Novel Aspects of RNA Regulation in Staphylococcus Aureus[END_REF]].

Figure 15 :

 15 Figure 15: Diversity of riboswitches and mechanisms of gene control in bacteria. Mechanisms of modulation of gene expression are highly divergent in prokaryotes and involve control of transcription, translation and mRNA stability. SD (Shine-Dalgarno), Pol (RNA Polymerase), ORF (Open Reading Frame) [From (Serganov & Nudler 2013)].

Figure 16 :

 16 Figure 16: Model of a regulatory cascade for methionine biosynthesis operon control. (i) At high amino acid concentration, branched-chain amino acids (BCAA) and GTP are bound to the CodY repressor, increasing its affinity for target DNA binding; downstream genes are repressed (small picture, bottom left). (ii) Low amino acid levels will trigger the stringent response due to stalled ribosomes, which leads to an increase in RelAmediated ppGpp alarmone synthesis resulting in less GTP. Subsequently, CodY dissociates from the DNA activating downstream transcription of the T-box leader RNA. The T-box acts as the crucial check-point sensing

Figure 17 :

 17 Figure 17: RNA polymerase interacts with 6S sRNA in E.coli. RNA synthesis by the " 70 -core RNA polymerase" complex (black). 6S sRNA (red) sequesters the polymerase complex during nutrient limitation (stationary phase of growth), and restrain gene expression to the ones controlled by an alternative  factor [From (Pichon & Felden 2007)].

Figure 18 :

 18 Figure 18: The accessory gene regulator (agr) quorum sensing system of S. aureus. [From (Novick & Geisinger 2008)].

Figure 19 :

 19 Figure 19: Regulatory circuits involved in virulence gene expression. The networks are based on the knowledge acquired from the literature (see the accompanying text). The transcriptional regulatory proteins are in black, the regulatory RNAs are in red and the target proteins are in purple. The transcriptional regulation is shown by black lines while post-transcriptional regulation is shown by red lines. Arrows corresponded to activation while bars corresponded to repression. Indirect regulation is given by dotted lines. The functional consequences of the regulation are also given. [From (Fechter et al. 2014)].

Figure 20 :

 20 Figure 20: RsaE controls metabolic pathways. Autoinducing peptide (AIP), tricarboxylic acid cycle (TCA). The plain and dashed lines indicate the direct and indirect gene regulations, respectively (red bars: inhibitions, black arrows: stimulations). [From (Guillet et al. 2013)].

Figure 21 :

 21 Figure 21: RsaA and its regulatory circuits. (A) Schematic drawing summarizing the regulatory

Figure 23 :

 23 Figure 23: Effect of hfq deletion on pigmentation in different S. aureus strains.

Figure 24 :

 24 Figure 24: Examples of regulatory RNAs and their mechanism of action in S. aureus. (A) Inactivation of rot mRNAs by RNAIII. C-rich sequence motifs of RNAIII (in red) are seed sequences binding to SD sequences of mRNA targets. The formation of a RNAIII-rot mRNA duplex prevents the small ribosomal subunit (30S) binding and promotes RNase III specific cleavages (grey arrows). (B) Repression of sbi mRNA translation by SprD. Three different regions of SprD base-pair with sbi mRNA 5'-UTR and the beginning of its coding sequence. The duplex prevents the formation of an initiation ribosomal complex. [From[START_REF] Fechter | Novel Aspects of RNA Regulation in Staphylococcus Aureus[END_REF]].

Figure 25 :

 25 Figure 25: Examples of RNase III functions. (a) Schematic view of S. aureus RNAIII structure. RNAIII is involved in the regulation of virulence genes by base-pairing with specific mRNAs (b) The region around the SD sequence of coa mRNA (encoding coagulase) base-pairs with the RNAIII helix H13 and is stabilized by a second interaction involving the RNAIII helixH7. RNase III degrades the coa mRNA-RNAIII duplex, both in the SD region and within the loop-loop interaction region. (c) RNase III degrades ds-RNAs including sense antisense RNA duplexes as exemplified by type I toxin-antitoxin systems. (d) Cleavage inside a stem-loop can give rise to a more stable mRNA, as demonstrated for the cold shock protein A cspA mRNA. Cleavage of the stem-loop releases the translation start codon and a new stem-loop protects the 5' end from RNase Jmediated degradation. [From (Bonnin & Bouloc 2015)].

  Gram-positive bacteria such as B. subtilis or S. aureus, no single-strand specific-RNA endonuclease RNase E is present. However, single-strand endonuclease RNase Y and two paralogs RNases named RNase J1 (formerly YkqC) and RNase J2 (formerly YmfA) were discovered and are functionally equivalent to RNase E in E. coli. In B. subtilis, the depletion of RNase Y (encoded by rny) generates pleiotropic effects: reduced biofilm formation, altered the expression of many genes involved in folate, amino acid biosynthesis and extracellular polysaccharide synthesis (Lehnik-Habrink et al. 2011).In S. aureus, the rny ortholog (formerly cvfA) was first identified in a screen for new virulence factors in silkworm and mouse infection models[START_REF] Kaito | Silkworm Pathogenic Bacteria Infection Model for Identification of Novel Virulence Genes[END_REF]. rny mutant showed a decrease of hemolysin production, and reduced virulence. Later, it was shown that CvfA protein has two domains: an RNA binding domain (KH domain), and a metaldependent phosphohydrolase domain (HD domain). The HD domain was required for the virulence phenotype[START_REF] Nagata | Phosphodiesterase Activity of CvfA Is Required for Virulence in Staphylococcus Aureus[END_REF]. Moreover, RNase Y was also shown to control the expression of SaeS/SaeR TCS, a global regulator of virulence. The sae operon has 4 overlapping transcripts from T1 to T4. RNase Y processes the T1 transcript leading to the stabilization of a T2 transcript(Marincola et al. 2012) (Figure26).

Figure 26 :

 26 Figure 26: Schematic representation of the saePQRS operon with primary and mature transcripts (T1-T4), the promoters (P1 and P3), the terminators (Term1 and Term2) and the cutting site (CS). Adapted from (Marincola et al. 2012).

A

  model was proposed in which specific 3'OH RNAs involved in hemolysin production were first cleaved by RNase Y producing 2',3'-cyclic RNAs. Then, 2',3'-cyclic RNAs are converted to 3'phosphorylated RNAs through hydrolysis of RNase Y. In this process, specific 3'OH RNAs and 2',3'-cyclic RNAs were sensitive to PNPase degradation while 3'phosphorylated RNAs were resistant to PNPase (Figure 27).

Figure 27 :

 27 Figure 27: S. aureus hemolysin production via RNA stability control by RNase Y (CvfA) and PNPase. A specific RNA (3'-OH RNA) required for hemolysin production cleaved by RNase Y or other endonucleases results in the production of 2',3'-cyclic RNA. Next, the 2',3'-cyclic RNA is converted to 3'-phosphorylated RNA by RNase Y. 3'-OH RNA and 2',3'-cyclic RNA are degraded by PNPase, whereas 3'-phosphorylated RNA is resistant to PNPase degradation. [From (Numata et al. 2014)].

Figure 28 :

 28 Figure 28: Regulatory mechanism of FasX with the ska mRNA. sRNAs are drawn in red, mRNAs in blue. Light blue, ribosome binding sites (RBS). Yellow symbols indicate ribosomes. Black arrows indicate unknown RNase action. [From (Brantl & Bruckner 2014)].

Figure 29 :

 29 Figure 29: Examples of regulatory RNAs in Clostridium. sRNAs are drawn in red, mRNAs in blue. Light blue, ribosome binding sites (RBS). Yellow symbols indicate ribosomes. Black arrows indicate unknown RNase action. [From (Brantl & Bruckner 2014)].

Figure 30 :

 30 Figure 30: Regulatory mechanism of LhrA and chiA mRNA. sRNAs are drawn in red, mRNAs in blue. Light blue, ribosome binding sites (RBS). Yellow symbols indicate ribosomes. Black arrows indicate unknown RNase action. [From (Brantl & Bruckner 2014)].

Figure 31 :

 31 Figure 31: Interplay between a metabolite-sensing riboswitch and a temperature-sensing RNA thermometer. Translation initiation of PrfA-encoding mRNA of Listeria monocyogenes at low temperatures (<30 o C) is hindered by a secondary structure that masks the Shine-Dalgarno (SD) site (bold). At host body temperature (37 o C), the secondary structure is partially disrupted, enabling docking of the ribosome and translation initiation. After translation of the prfA mRNA, PrfA activates the transcription of virulence genes that are important for host infection. The truncated SAM riboswitch element A (SreA), which is encoded upstream of lmo2419 and expressed only when levels of S-adenosyl methionine (SAM) are high (such as when the bacterium is inside the host), can function in trans by binding to the prfA RNA thermometer. The interaction between SreA and the prfA mRNA leads to diminished expression of PrfA. The exact mechanism by which this interaction hampers ribosome binding remains to be elucidated. SreA and prfA interaction sites are depicted in red and yellow. [From (Kortmann & Narberhaus 2012)].

Figure 32 :

 32 Figure 32: SR1, a B. subtilis trans-encoded sRNA with dual-function. +, activation; -, repression. CcpA and CcpN repress sr1 transcription under glycolytic conditions. TF is a novel transcription factor that activates sr1 transcription at cold-shock. The antisense RNAs are indicated in red, the sense RNAs in blue, RBS in light blue. [From (Brantl & Brückner 2014)].

Figure 33 :

 33 Figure 33: Riboswitch-based regulation. The eut operon contains genes involved in ethanolamine metabolism in bacteria. (A) EutV is phosphorylated and activated by EutW in response to ethanolamine. Active EutV forms a dimer that binds to adjacent RNA hairpins in the target transcript. Binding at these sites leads to antitermination; thus, transcription of the operon is turned ON, but this can only happen in the presence of vitamin B12. (B) In the absence of vitamin B12, a noncoding RNA is generated that sequesters EutV; thus, transcription of the operon is turned OFF. (C) In the presence of vitamin B12, the riboswitch blocks transcription of the noncoding RNA through a structural change that produces a terminating hairpin RNA (T). Active EutV protein is then free to bind to the target transcript and promote expression of ethanolamine metabolic genes. [From (Chen & Gottesman 2014)].

  a pilot experiment, a DNA-seq bank was made from forty different conditions and a deepsequencing experiment was performed. Unexpectedly, about 80% of the DNA barcode sequences were associated with experiment identifiers (forward compared to reverse) coming from two independent experiments. As amplified tags each experiment differ only by their 5 terminal nucleotides, the denaturation steps and PCR-amplification during DNAseq bank constructions lead to illegitimate pairing of identical barcodes coming from different experiments and artefactual results (data not shown). We solved this technical issue by removing the amplification step from the standard DNA-seq bank construction protocol. The resulting protocol adapted to deep sequencing technology is time saving, increases the response linearity, and cheaper if several conditions are pooled, as compared to the array technology.

  were incubated for 1 h at 37°C with the lysis solution containing lysostaphin (10 mg/ml) (Sigma-Aldrich, St. Louis, MO, USA). PCR amplifications were performed using high fidelity Phusion DNA Polymerase (Thermo Scientific Finnzymes) for cloning or Taq Polymerase (Fermentas) for verification following supplier's recommendations. DNA concentration was measured using Nanodrop Spectrophotometer ND-1000 (Peqlab, Erlangen, Germany). For transformation, we use chemically-competent cells for E. coli, and electro-competent cells for S. aureus. As pMAD2 derivatives carry the bgal gene encoding ß-galactosidase, their presence in S. aureus was visualized by formation

Figure 1 Fitness

 1 Figure 1

Figure 3 Competition

 3 Figure 3

Figure 4 Growth

 4 Figure 4

Figure 5 Growth

 5 Figure 5

Figure 6 Complementation

 6 Figure 6

Figure 7 Plasmids

 7 Figure 7

Figure S2 .

 S2 Figure S2.

Figure 34 : 4 .Figure 2 : 4 .Figure 3 :Figure 4 :

 3442434 Figure 34: Competition assay at pH 5.4. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) at pH 5.4 compared to a reference at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

Figure 5 :

 5 Figure 5: Competition assay at NaCl 1.5M. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) at NaCl 1.5M compared to a reference at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

Figure 6 :

 6 Figure 6: Competition assay at H 2 0 2 0.1mM. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) at H 2 0 2 0.1mM. compared to a reference at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

Figure 7 :

 7 Figure 7: Competition assay in RPMI medium. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in RPMI medium. compared to a reference in BHI medium at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

Figure 8 :

 8 Figure 8: Competition assay in RPMI no-folate medium. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in RPMI medium. compared to a reference in BHI medium at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

  , upper histograms). However, when the population underwent stationary phase (Sampling 2), the quantity of mutant sau30 varied either up (RMPI anaerobiosis) or down (BHI anaerobiosis) but with an unusual great variability making the results difficult to interpret (Figures 9 & 10, lower histograms). In contrast, mutant teg49 accumulated in anaerobic RPMI medium (Figures 10).

Figure 35 :

 35 Figure 35: Competition assay in anaerobic BHI medium. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in anaerobic BHI medium. compared to a reference in aerobic BHI medium at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

Figure 10 :

 10 Figure 10: Competition assay in anaerobic RPMI medium. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in anaerobic BHI medium. compared to a reference in aerobic BHI medium at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

Figure 11 :

 11 Figure 11: Competition assay in BHI medium containing DIP (1.4mM). Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) at DIP 1.4mM compared to a reference at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

Figure 12 :

 12 Figure 12: Competition assay in BHI medium containing human serum (10%). Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (xaxis) in BHI medium containing human serum (10%) compared to a reference at 37°C. Upper and lower histograms correspond to Sampling 1 and 2, respectively. Data are shown as average values and the standard deviation of triplicate samples is indicated.

Figure 13 :

 13 Figure 13: Competition assay from blood samples in mouse model. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in blood samples compared to an uninfected reference sample. Data are shown as average values and the standard deviation of three samples is indicated.

Figure 14 :

 14 Figure 14: Competition assay from spleen samples in mouse model. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in blood samples compared to an uninfected reference sample. Data are shown as average values and the standard deviation of three samples is indicated.

Figure 15 :

 15 Figure 15: Competition assay from kidney samples in mouse model. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in blood samples compared to an uninfected reference sample. Data are shown as average values and the standard deviation of three samples is indicated.

Figure 17 : 2 a

 172 Figure 17: Competition assay from liver samples in mouse model. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in blood samples compared to an uninfected reference sample. Data are shown as average values and the standard deviation of ten samples in mix 2 is indicated.

Figure 1 .

 1 Figure 1. Overview of the Hybrid-trap-seq procedure. Synthetic sRNAs (RNAIII, RsaA, RsaE and RsaH) generated by in vitro transcription were biotinylated and incubated with magnetic streptavidin beads, to obtain sRNA-bound beads. Each of them was mixed with pooled total RNA samples of S. aureus grown in 16 different conditions. Unbound RNAs were removed by washing steps using magnetic separation. RNAs bound to sRNA-bound beads were then eluted and sequenced by RNA-seq technology. Reads were aligned to the chromosome sequence (NCTC8325) and visualized. Specifically retained RNAs corresponding to RNA targets of each sRNA-bait (an example with RNAIII is presented) were identified by differential expression analyses. The complete protocol is presented in Supporting information.

Figure 2 .

 2 Figure 2. Examples of sRNA-dependent read enrichment regions. Selected Artemis genome viewer windows show i) read density profiles of RNAs trapped with sRNAs (Hybrid trap), ii) reads from RNA-seq of HG003 pooled total RNA extractions (Transcriptome), and iii) genome annotation with blue boxes indicating open reading frames (Annotation). For the complete set of putative and confirmed targets, see Dataset S1 and Table 1, respectively. Panels A, B, C, and D correspond to read density profiles enriched with RsaA, RsaE, RsaH, and RNAIII trapping experiments, respectively. Read density profiles of RNAs positioned above (in red) or below (in green) the horizontal line indicate reads mapping on the clockwise and counterclockwise genomic DNA strands, respectively; scales were normalized independently for each gene using the maximum and minimum density values among the four datasets.

Figure 3

 3 Figure 3. Analysis of the targetmatching regions of RsaA, RsaE and RsaH.

Figure 4 .

 4 Figure 4. In vivo effect of sRNAs on their targets. Total RNAs were extracted from strains expressing conditionally the indicated sRNAs upon the addition of anhydrotetracycline (aTc, 1 mM) to the medium. (-), prior to aTc addition; (+), 5 min induction. The quantity of the indicated sRNA-targets was visualized by Northern blot experiments. Hu mRNA was used as a loading control for normalization.Numbers correspond to the SAOUHSC nomenclature.

Figure 5 .

 5 Figure 5. Staphylococcus aureus sRNA-controlled pathways identified by Hybrid-trap-seq.

  Cells pellets were resuspended into 400 μL of Lysis buffer (4 M guanidine thiocyanate, 25 mM sodium acetate pH 5.2, 5 g/L N-laurylsarcosinate), transferred into FastPrep tubes containing 0.6 g of glass beads (G4649, Sigma-Aldrich) and 400 µL of acid phenol:chloroform:IAA(25:24:1). Bacteria were mechanically lysed by using the Fastprep apparatus (MP Biomedicals) with 3 cycles of 45 s at speed 6.0 separated by incubation on ice during 5 min. After lysis, tubes were centrifuged 15 min at 17,900 g at 4 °C. The aqueous phase was acid phenol extracted, isopropanol precipitated and the pellet resuspended in RNase-free water. The RNA concentration of samples was measured using a NanoDrop 1000 Spectrophotometer (NanoDrop Technologies, Inc.). The quality of the RNA preparations was assessed by capillary electrophoresis using RNA Nano chips with a Bioanalyzer Agilent 2100 (Agilent Technologies, Palo Alto, USA). Total RNA extracts were treated using the Turbo DNase I (Ambion, Foster City, CA, USA) before qRT-PCR.Total RNA samples were extracted in 16 different biological conditions as described below. i) 8 samples harvested in the course of growth: Overnight cultures were diluted 2000 times in BHI medium and incubated at 37°C under shaking agitation (180 rpm). Cells were harvested in exponential phase (at OD 600nm 0.6, 1.8 and 3.3), transition phase (at OD 600nm 4.5 and 7.2), early stationary phase (at OD 600nm9.8 and 12.8) and late stationary phase (24 hours). ii) 6 samples harvested under stress conditions: Exponential growing cells (at OD 600nm 0.6) were submitted before RNA extraction to cold shock (15 min at 10°C), heat shock (10 min at 48°C), oxygen limitation (the exponential growing culture was transferred into a 50 mL Falcon tube fully filled and was incubated during 30 min under static condition), alkaline stress (10 min after addition of KOH 30 mM), oxidative stress (10 min after addition of H 2 O 2 10 mM) or disulfide stress (10 min after addition of diamide 1 mM). iii) 1 sample harvested under iron-depleted condition: Overnight culture was diluted in BHI supplemented with 2,2-dipyridyl at 1.4 mM and incubated for growth until OD 600nm reached 1. iv) 1 sample from cells grown on BHI-agar plates: Exponential growing cells were diluted at ~5.10 3 CFU/mL, 100 µl were spread on BHI-agar plates and incubated 16 h at 37°C. Colonies were resuspended in lysis buffer for RNA extraction.

( 50 :

 50 50) during 5 min in the dark. 3'-OH oxidized RNAs were precipitated during 5 min on ice by adding 750 µl ethanol 100 %, then harvested by centrifugation at 13000 rpm during 20 min at 4°C. The pellets were resuspended in 100 µl of biotinamidocaproyl hydrazide 10 mM (Sigma-Aldrich, B3770) and incubated 2 h at 37°C. One hundred µl of NaBH 4 200 mM and 200 µl Tris-HCl 1 M pH 8 were added to the samples. After 30 min at 4°C in the dark, the reduction reaction was stopped by ethanol precipitation. RNA pellets were resuspended in RNase-free water. Full length RNAs were 5% urea PAGE purified as recommended in the T7 MEGAshortscript kit procedure. For each Hybrid-trap-seq experiment, 25 µl of MasterBeads pre-coated with streptavidin (Ademtech, Pessac-France) were equilibrated in binding buffer (20 mM Tris-HCl, 0.5 M NaCl pH 8) then incubated 10 min at 20°C with 100 pmoles of biotinylated sRNA dissolved in binding buffer. Unbound sRNAs were removed by magnetic separation, and then sRNA-bound streptavidin beads were washed twice with 100 µl of binding buffer. For each Hybrid-trap-seq experiment, 50 µg of pooled total RNA sample were prepared in 20 mM Tris-HCl, 0.5 M NaCl pH 8, EDTA 1

  2.5 through the web interface at http://rna.informatik.uni-freiburg.de with parameters "Exact Number of Base Pairs in Seed" = 5 and "Max Number of Unpaired Bases" = 1. Input sequences were the complete sRNA sequence and, for each putative target, the region from the TSS to 100 nucleotides past the start codon. TSSs were defined from the above sequencing of total pooled RNA (62M 40 nt. reads) as described elsewhere (Toffano-Nioche et al. 2013). Briefly, reads were aligned onto the S. aureus genome using Bowtie V.1 [(9); options -v 2 -m 1] and the resulting BAM files were analyzed using the Det'rprok pipeline (Toffano-Nioche et al. 2013). For non-coding putative targets, the region analyzed was the entire transcript identified using the same protocol. Coordinates of coding and non-coding relevant transcripts are provided (Table

Fig. S1 .

 S1 Fig. S1. Distribution of IntaRNA hybridization energy values obtained when matching each sRNA to its set of hybrid-trap-seq targets (RNA vs targets), compared to energy values obtained when matching the same sRNA to the same number of random genes (RNA vs rnd). P-values for hypothesis of identical distributions are computed using Wilcoxon's test.

Fig. S2 .

 S2 Fig. S2. Secondary structures of RsaA (A), RsaE (B) and RsaH (C) predicted from a structural alignment of homologous sequences, as provided by the RFAM database (20). Color scale indicates evolutionary conservation at each position (red: most conserved). Boxes around sequences indicate predicted seed matching regions as explained in Fig. 3. Structures are drawn using Varna (21). RFAM entries: RsaA: RF01816; RsaE: RF01820; RsaH: RF01821. [Experimental structures were also previously reported (22)]

Fig. S3 .

 S3 Fig. S3. Model for the standard S. aureus SD motif, identified by MEME (14) using all HG003 available 5' UTR regions (see Matérials and Method).

Figure 1 .

 1 Figure 1. S. aureus NCTC8325 prophages prevent the selection of rnc deletion. Upper part: simplified scheme of the NCTC8325 lineage. See ref. 26 for detailed NCTC8325 genealogy. Table, corresponding strain genotypes and frequency of rnc deletions obtained using pMAD2-DErnc (Material and Methods). a, b and c indicate that 50, 10 and 20 colonies were tested by PCR for the presence of rnc deletions, respectively.

Figure 2 .

 2 Figure 2. SapTA is deleterious in the absence of RNase III. (A) Growth curves of RN4220 and derivatives are presented as indicated. Growth curves were done in triplicate in 96-Well multiwell plates covered with a semipermeable film (4titude, Bagneux France) under constant vigorous shaking using the microplate reader CLARIOstar (BMG Labtech, Ortenberg, Germany). (B) Stereomicroscope (Motic, Wetzlar, Germany) photographs of the indicated strains grown on BHI plates after 18 hours of culture. Same settings were used for all photographs.

Figure 3 .

 3 Figure 3. RNase III is involved in sapTA expression. Northern blot analysis of sapT mRNA and SapA in RN4220 and RN4220 Δrnc. Total RNAs were prepared from cultures harvested at OD 600 0.4, 2, 4, 6 and in stationary phase as indicated. Probes against sapT mRNA, SapA and 5S were used as indicated (see Material and Methods).

Figure 4 .

 4 Figure 4. RNase III alters phage growth. (A) Phage spot dilution plating assay of Ф11 on RN4220 and RN4220 Δrnc. (B) Stereomicroscope observation after 8h of Ф11 and Ф80α plaques spotted on RN4220 and RN4220 Δrnc. Plaques are clearer in the absence of RNase III.

Figure S1 .

 S1 Figure S1. Prophage loci with antisense transcription in HG003. RNA-seq results are visualized with Artemis sequence editor tool. 1 Tracks were added to the classical view as described. 2 (Top) Ln of read coverage track; forward and reverse sequences are in red and in bleu, respectively. (Middle) BamView of mapped reads; forward and reverse sequences are above and under the line, respectively. (Botton) HG003 Artemis representation using NCTC8325 nomenclature. (white boxes) CDSs; (brown boxes) annotated proteins from Φ12; (pink boxes) annotated proteins from Φ11; (green boxes) annotated proteins from Φ13; (small vertical black lines) stop codon for the six DNA reading frames.ϕ1 1

  R indicate forward or reverse orientation with respect to the chromosome annotation, respectively.

Figure 18 :

 18 Figure 18: Summary result of fitness experiments in different growth conditions and in a mouse model. Red line: under-represented. Green line: over-represented. Black line: disappearance.

Figure 20 :

 20 Figure 20: Artemis view of Sau6836 in our transcriptome HG003.

Table 1 :

 1 Summary of experimentally validated regulatoryRNAs in S. aureus ........................

Table 2 :

 2 Ribonucleases in S. aureus .........................................................................................

	ABBREVIATIONS

Table 1 :

 1 Summary of experimentally validated regulatory RNAs in S. aureus a[START_REF] Tomasini | The Importance of Regulatory RNAs in Staphylococcus Aureus[END_REF]

	Study	Strain	sRNA discovery	Experimentally validated sRNAs	e	Experimental	Target and mechanism	Comment
		used	methodology			validation
			(number of in silico			method
			predicted sRNAs)
	(Roberts et al.	UAMS-1	Gene chip analysis	SSR42 (srn_4470, RsaX28, Teg27, sRNA363)	NB, RT-PCR	Spa, hla, hglC, lukF
	2006)							Unknown
	(Pichon & Felden	Mu50	Bioinformatic	SprA				ABC transporter (SA2216),
	2005) and (Sayed et al. 2011)	(clonal Complex 5)	predictions	SprA2 (srn_4550, WAN014FZW, IGR2049, IGR8bis, Teg26as, sRNA371), SprA3 (IGR2125), SprB (srn_3600, Teg9, IGR18), SprC (srn_3610, Teg10), SprD (srn_3800, Teg14_sRNA300), SprE, SprF, SprG, SprFG2,	NB NB NB	b b b	possible antisense sRNA Unknown, SprA2 encodes a cytolytic peptide Housekeeping ncRNAs
				SprFG3
				4.5S RNA (ffs, Teg42, IGRLF1, WAN01CBPQ,
				sRNA98), 6S RNA (Teg97, ssrS, ssr80, IGR2,
				WAN01CC8T, sRNA256), RNAIII (srn_3910,
				sRNA317), tmRNA (tmR, WAN014GIY,
				Teg150, ssrA, sRNA166), RNase P (RseP, rnp,
				Teg65, IGR1215, sRNA240)
	(Geissmann et al.	RN6390,	Bioinformatic	RsaE (srn_2130, RsaON, Sau20, Teg92, IGR6,	NB, PE, RACE	Masking of ribosomal binding site	Genetic manipulation
	2009)	COL,	predictions and	sRNA183),		NB, PE, RACE	for oppB, sucD, SA0873	demonstrated a role
		Newman, HG001	experimental validation	RsaA (srn_1510, rsaOJ, Teg88, sau64, IGR1, (srn_1590, Teg90, sRNA135), RsaD IGR14, sRNA132), RsaB (srn_3410), RsaC			Unknown	for RsaE in controlling metabolic pathways
				(srn_1640, Teg91, sRNA138), RsaF, RsaG
				(srn_0510, Teg93, sRNA31), RsaH (srn_1910,
				rsaOK, Teg94, sau6059, IGR7, sRNA162), RsaI
				(srn_4390, rsaOG, Teg24, sRNA356), RsaJ
				(srn_4530, sprAs2prime, Teg96, sau5837,
				sRNA369), RsaK (srn_0440, Teg38, sRNA27)

a Validated by Northern blot, RNA extremity mapping, or RT-qPCR. b Also experimentally validated using Northern blot in the study by

(Abu-Qatouseh et al. 2010

). c Originally described by

(Anderson et al. 2006

). d Previously described and validated. NB, Northern blot; PE, primer extension; RACE, random amplification of cDNA ends; RT-PCR, real-time PCR. Several long and stable RNAs (SSR) expressed under particular conditions of growth have been assigned by microarrays

S. aureus sRNA functions 4.1 RNA chaperone Hfq: a controversial factor

	Hfq (aka HF-I, host factor-I) encoded by the hfq gene, is a RNA-binding protein first
	discovered in E. coli as a essential host factor for bacteriophage Q replication (Franze de
	Fernandez et al. 1968; Franze de Fernandez et al. 1972). Hfq facilitates the imperfect
	complementary pairings of sRNAs and their targets by stabilizing the interaction between
	the two RNA molecules and/or by increasing their local concentration. In many bacteria,
	including E. coli, Hfq is required for sRNA activities and contributes to the recruitment of the
	endoribonuclease RNase E (Morita et al. 2005; Urban & Vogel 2007; Bandyra et al. 2012).

Table 2 :

 2 Ribonucleases in S. aureus. [From(Bonnin & Bouloc 2015)].

	Ribonuclease	Gene	Function a	Amino	acid	Amino	acid	Nomenclature	Nomenclature	Essentiality
				identity between	identity between	N315	NCTC8325	b
				NCTC8325 and B.	NCTC8325 and E.
				subtilis168		coli	MG1655
				orthologs c		orthologs c
	RNase III	rnc	ds-RNA endonuclease *	0.49		0.34		SA1076	SAOUHSC_01203 N
	Mini-III	mrnC	ds-RNA endonuclease ¤	0.56		None		SA0489	SAOUHSC_00512 N b
	RNase Y	rny/cvfA	ss-RNA endonuclease *	0.69		None		SA1129	SAOUHSC_01263 N
	RNase J1	rnjA	strong 5'-3' exonuclease activity *	0.67		None		SA0940	SAOUHSC_01035 N**
			ss-RNA endonuclease
	RNase J2	rnjB	weak 5'-3' exonuclease activity *	0.50		None		SA1118	SAOUHSC_01252 N**
			ss-RNA endonuclease?
	RNase P	rnpA	Endonucleolytic cleavage of RNA, removing	0.49		0.24		SA2502	SAOUHSC_03054 Y
			5'-extranucleotides from tRNA precursor
			with rnpB ribozyme *
	RNase Z	Rnz	Endonucleolytic cleavage of RNA involved	0.45		0.41		SA1335	SAOUHSC_01598 Y
			in removing extra 3' nucleotides from the
			tRNA precursor ¤

a Function: * demonstrated experimentally; ¤ function based on results of B. subtilis or E. coli studies.

b Essentiality: Y, demonstrated experimentally using transposon mutagenesis

[START_REF] Chaudhuri | Comprehensive Identification of Essential Staphylococcus Aureus Genes Using Transposon-Mediated Differential Hybridisation (TMDH)[END_REF]

; N not essential demonstrated experimentally, N b not essential based on B. subtilis studies. ** RNase J1 and J2 are essential at 42°C but not at lower temperatures

[START_REF] Chaudhuri | Comprehensive Identification of Essential Staphylococcus Aureus Genes Using Transposon-Mediated Differential Hybridisation (TMDH)[END_REF][START_REF] Linder | Transcriptome-Wide Analyses of 5'-Ends in RNase J Mutants of a Gram-Positive Pathogen Reveal a Role in RNA Maturation, Regulation and Degradation[END_REF]

).

Table S1 : Bacterial strains

 S1

	SAPhB390 Table S2: Plasmids pDEteg60::tag23 pDEssr42::tag50	As HG003 sau6851::tag32 pMAD2 derivative for chromosomal substitution pMAD2 derivative for chromosomal substitution	This study This study This study
	Strains SAPhB392 SAPhB393 Name pDErsaB::tag25 pDEteg155::tag53 SAPhB395 pJET pDEsau69::tag27 pDEteg32::tag54 E. coli DH5αZ1 SAPhB397 SAPhB402 S. aureus SAPhB400 SAPhB401 pMAD2 pDEsau40::tag29 pMAD pDEsau30::tag28 pDEsprD::tag57	Relevant genotype As HG003 sau11::tag33 of teg60 locus with tag23 sequence of ssr42 locus with tag50 sequence As HG003 sau27::tag36 Relevant genotype pMAD2 derivative for chromosomal substitution pMAD2 derivative for chromosomal substitution of rsaB locus with tag25 sequence of teg155 locus with tag53 sequence As HG003 teg108::tag37 rep (pMB1), bla (Ap R ), eco47IR, P lacUV5 , T7 pMAD2 derivative for chromosomal substitution pMAD2 derivative for chromosomal substitution F -(80dlacZΔM15) Δ(lacZYA-argF)U169 deoR recA1 hsdR17(r k _ m k _ ) endA1 supE44  -thi-1 gyrA(Nal r ) relA1 tetR + lacR + Sp r promoter of sau69 locus with tag27 sequence of teg32 locus with tag54 sequence As HG003 sau85::tag38 As HG003 sau6353::tag42 bla (Ap R ), ermC (Ery R ) of sau40 locus with tag29 sequence As HG003 sau6528::tag40 As HG003 sau6387::tag41 rep pE194 ts , rep pBR322, pclpB promoter, bgaB, pMAD2 derivative for chromosomal substitution bla (Ap R ), ermC (Ery R ) of sau30 locus with tag28 sequence of sprD locus with tag57 sequence rep pE194 ts , rep pBR322, pclpB promoter, bgaB, pMAD2 derivative for chromosomal substitution pMAD2 derivative for chromosomal substitution	This study Reference This study This study This study Reference This study Fermentas This study This study This study (Lutz & Bujard, 1997) This study unpublished Bonnin et al. This study This study 2004) This study (Arnaud et al, This study This study
	RN4220 SAPhB404 pDEteg116::tag30	Restriction-defective derivative of 8325-4 As HG003 rsaE::tag45 pMAD2 derivative for chromosomal substitution	(Kreiswirth et al, 1983) This study results This study
	HG003 SAPhB194 SAPhB406 pDErsaA::tag1 SAPhB302 pDEsau6569::tag31 pMAD2 derivative for chromosomal substitution NCTC8325 derivative rsbU and tcaR repaired, agr+ As HG003 rsaA::tag1 As HG003 teg130::tag46 pMAD2 derivative for chromosomal substitution of teg116 locus with tag30 sequence As HG003 RNAIII::tag47 of rsaAlocus with tag1 sequence pDEsau60::tag3 pMAD2 derivative for chromosomal substitution of sau6569 locus with tag31 sequence SAPhB343 As HG003 sau60::tag3 SAPhB409 As HG003 rsaH::tag49 pDErsaD::tag6 pMAD2 derivative for chromosomal substitution of sau6851 locus with tag32 sequence SAPhB407 As HG003 sau19::tag48 of sau60 locus with tag3 sequence pDEsau6851::tag32 pMAD2 derivative for chromosomal substitution	(Herbert et al, 2010) This study This study This study This study This study This study This study This study This study This study This study
	SAPhB345 SAPhB347 SAPhB349 SAPhB416 pDErsaG::tag11 SAPhB412 pDEsau11::tag33 SAPhB415 pDEteg24::tag9 pDEsau27::tag36	As HG003 rsaD::tag6 As HG003 teg24::tag9 As HG003 rsaG::tag11 As HG003 teg32::tag54 pMAD2 derivative for chromosomal substitution of sau27 locus with tag36 sequence As HG003 ssr42::tag50 of rsaD locus with tag6 sequence pMAD2 derivative for chromosomal substitution As HG003 teg155::tag53 pMAD2 derivative for chromosomal substitution of sau11 locus with tag33 sequence of teg24 locus with tag9 sequence pMAD2 derivative for chromosomal substitution	This study This study This study This study This study This study This study This study This study This study
	SAPhB353 SAPhB417 pDEteg108::tag37	As HG003 ssrS::tag12 As HG003 sprD::tag57 of rsaG locus with tag11 sequence pMAD2 derivative for chromosomal substitution	This study This study This study
	SAPhB360 pDEssrS::tag12	As HG003 sau6041::tag14 pMAD2 derivative for chromosomal substitution of teg108 locus with tag37 sequence	This study This study
	SAPhB363 pDEsau85::tag38 SAPhB365 pDEsau6041::tag14 pMAD2 derivative for chromosomal substitution of ssrS locus with tag12 sequence pMAD2 derivative for chromosomal substitution As HG003 sau41::tag15 As HG003 sau6428::tag16 of sau85 locus with tag38 sequence SAPhB366 As HG003 sau6836::tag17 pDEsau41::tag15 pMAD2 derivative for chromosomal substitution of sau6528 locus with tag40 sequence of sau6041 locus with tag14 sequence pDEsau6528::tag40 pMAD2 derivative for chromosomal substitution	This study This study This study This study This study This study This study
	SAPhB368 pDEsau6387::tag41 pMAD2 derivative for chromosomal substitution As HG003 teg147::tag18 of sau41 locus with tag15 sequence	This study This study
	SAPhB370 pDEsau6428::tag16 pMAD2 derivative for chromosomal substitution As HG003 teg47::tag19 of sau6387 locus with tag41 sequence SAPhB372 As HG003 teg49::tag20 pDEsau6836::tag17 pMAD2 derivative for chromosomal substitution of sau6353 locus with tag42 sequence of sau6428 locus with tag16 sequence pDEsau6353::tag42 pMAD2 derivative for chromosomal substitution	This study This study This study This study This study
	SAPhB374 pDErsaE::tag45	As HG003 sau6053::tag21 of sau6836 locus with tag17 sequence pMAD2 derivative for chromosomal substitution	This study This study
	SAPhB376 pDEteg147::tag18	As HG003 teg58::tag22 pMAD2 derivative for chromosomal substitution of rsaE locus with tag45 sequence	This study This study
	SAPhB378 pDEteg130::tag46	As HG003 teg60::tag23 of teg147 locus with tag18 sequence pMAD2 derivative for chromosomal substitution	This study This study
	SAPhB380 pDEteg47::tag19 SAPhB382 pDEteg49::tag20 pDERNAIII::tag47	As HG003 rsaB::tag25 pMAD2 derivative for chromosomal substitution of teg130 locus with tag46 sequence As HG003 sau69::tag27 pMAD2 derivative for chromosomal substitution of RNAIII locus with tag47 sequence of teg47 locus with tag19 sequence pMAD2 derivative for chromosomal substitution	This study This study This study This study This study
	SAPhB383 pDEsau19::tag48	As HG003 sau30::tag28 of teg49 locus with tag20 sequence pMAD2 derivative for chromosomal substitution	This study This study
	SAPhB384 pDEsau6053::tag21 pMAD2 derivative for chromosomal substitution As HG003 sau40::tag29 of sau19 locus with tag48 sequence SAPhB386 As HG003 teg116::tag30 pDEteg58::tag22 pMAD2 derivative for chromosomal substitution of rsaH locus with tag49 sequence of sau6053 locus with tag21 sequence pDErsaH::tag49 pMAD2 derivative for chromosomal substitution	This study This study This study This study This study
	SAPhB388	As HG003 sau6569::tag31 of teg58 locus with tag22 sequence	This study

Table S3 : Primers to generate tagged deletion.

 S3 Up and Dw refer to upstream and downstream loci of the referred gene, respectively. F and R indicate that concerned primers are in the Forward or Reverse orientation with respect to the chromosome annotation, respectively.

	RsaG DwF RsaOI UpR Sau-30 UpF Sau-27 DwR Teg130 DwF Table S4: Tag sequences ACCCCACAACCTAGGTATATAGCGGTGTCAATATTGTAGGG GCGTATGGACCTAGGTATATACGGCTAATTACAGTTCTCAATTT GAATTCGAGACCGCTAGCGCGCTTCCATCGCCTCAGATAA GATATCGGATCCGAGACCCTCGGAAAATTCGCTGGTCTTA ACCCCACAACCTAGGTATATCACTCACTCCTTGTGTACATGC
	Name* RsaG DwR RsaOI DwF Sau-30 UpR Teg130 DwR Teg32 UpF Name Sequence* Sequence (5' to 3') GATATCGGATCCGAGACCCTTTCAACAACATCAGCCAGAA ACCCCACAACCTAGGTATATAGGCAGGTTTACCTGATAAAAA GCGTATGGACCTAGGTATATAACCCAGTCAATGTCATATACAGC GATATCGGATCCGAGACCCTGGAAAGAGGTTATAAGTTATGCCAAA GAATTCGAGACCGCTAGCGCTCTTCCGTTATAACCCCTCA
	RsaOI DwR Sau-30 DwF Teg108 UpF Teg32 UpR	GATATCGGATCCGAGACCCTTGACATTGATTAAGTAACTTTTCAGGA ACCCCACAACCTAGGTATATTCGTTGCACTCATTTGCTTT GAATTCGAGACCGCTAGCGCGAAAATAGAATTTTTAATAGGGACGTT GCGTATGGACCTAGGTATATGCAATTCGTATATTTTGCCAATG
	Tag_random ssrS UpF Sau-30 DwR Teg108 UpR RNAIII(agrA) UpF GAATTCGAGACCGCTAGCGCCCTGAAATGTGGAATAATGGCTA TTGTGGGGTACAGCAATGACAAGCTTN 40 AAGCTTATTGCATAGCTGCGTA GAATTCGAGACCGCTAGCGCGCAGCACCCATACTGGAAAT GATATCGGATCCGAGACCCTTACTGATGAAGCGCAAAACG GCGTATGGACCTAGGTATATAATATCCATTCACCATATGATTTTT Teg32 DwF ACCCCACAACCTAGGTATATTTGGCATTTCCAAAATATCACTT tag1
	TGGA GCGTATGGACCTAGGTATATATGGGTTTTCTTGCAGCGTA GAATTCGAGACCGCTAGCGCACTGCTCGTTATGCGGCTAT GCGTATGGACCTAGGTATATTGATGAAGCTAGTTTGATCAATTTCAC ACCCCACAACCTAGGTATATTCAGTCAGGAGGGACTTTCC RNAIII(agrA) UpR GCGTATGGACCTAGGTATATAGGGCGAAATGGGTTCTTAC ssrS UpR Teg49 UpF New Sau-30 UpR Teg108 DwF Teg32 DwR GATATCGGATCCGAGACCCTTTTGATGATGATTCAAGATAGTATGG
	Tag_F ssrS DwF Teg49 UpR Teg108 DwR RNAIII(agrA) DwF ACCCCACAACCTAGGTATATTTAAGTATTTATTTCCTACAGTTAGGC GGTCTCATGTGTTGTGGGGTACAGCAATGAC ACCCCACAACCTAGGTATATTTAAAATTTAGTGACGAATTCGCAAAG GCGTATGGACCTAGGTATATTCACTGTGTCTAATGAATAATTTGTTT GATATCGGATCCGAGACCCTAATATTTTTCCGTTGAGTGAATGA
	Tag_R ssrS DwR Teg49 DwF RsaOV UpF RNAIII(agrA) DwR GATATCGGATCCGAGACCCTTTTTGGTACTTCAACTTCATCCA GGTCTCTGAGATCCATACGCAGCTATGCAAT GATATCGGATCCGAGACCCTGGTGCAGCTGAACAATATACTCG ACCCCACAACCTAGGTATATTTCCGATTGATAACGGGTAA GAATTCGAGACCGCTAGCGCCGCCAATTGTAATCTGTCCA sprD UpF GAATTCGAGACCGCTAGCGCGGACGCCTATGACTACAGTTACG
	Teg49 DwR RsaOV UpR Sau-85 UpF sprD UpR	GATATCGGATCCGAGACCCTACTCATTCACCAGCCTTTGC GCGTATGGACCTAGGTATATTTAGGTGACTTAAAAGAAATCAGATG GAATTCGAGACCGCTAGCGCTTTGCTGTTTATTCGTTTGATGA GCGTATGGACCTAGGTATATGCATTTCGGTGCTTACCTTT
	RsaA UpF Sau-6041 UpF RsaOV DwF Sau-85 UpR RNAIII UpF sprD DwF	ATATGGTCTCGAATTCCAAACGCAGTAACCAATGCT GAATTCGAGACCGCTAGCGCATTTATCGCAACCGGATCAT ACCCCACAACCTAGGTATATTGGTAAAAGTAAAACGCAACGA GCGTATGGACCTAGGTATATTTGAGCTTAGGAAATCGATAGG GAATTCGAGACCGCTAGCGCCCTGAAATGTGGAATAATGGCTA ACCCCACAACCTAGGTATATTGAAAATTTGAACACATTGCTG
	RsaA UpR Sau-6041 UpR Sau-6053 UpF RsaOV DwR Sau-85 DwF RNAIII UpR sprD DwR	AAGCTTGGTCTCACACACTTTTTATACTTCAAGAGAATTTTAAC GCGTATGGACCTAGGTATATAAATTTGTGTACTATTCTTCGTCAAA GAATTCGAGACCGCTAGCGCCGTTGAAGTAAGCCCGTTTG GATATCGGATCCGAGACCCTGCGCCACCATTTCTTAAGTT ACCCCACAACCTAGGTATATGATTTACCAGATGACATATAACAGCA GCGTATGGACCTAGGTATATATCATTATGAGACCCGCCGT GATATCGGATCCGAGACCCTTTCATTAGTTTTACCAGGACCATT
	RsaA DwF Sau-6041 DwF Sau-6053 UpR Sau-85 DwR RNAIII DwF	ATATGGTCTCGGATCTATGCAGTTGATTGGGCAT ACCCCACAACCTAGGTATATAGTGCAAAAGTGCAAATTGA GCGTATGGACCTAGGTATATAATTCGATTATACAATTGAGCTGTT GATATCGGATCCGAGACCCTGGCGGTGCAATTGAATATAG ACCCCACAACCTAGGTATATCATGCTAAAAGCATTTATTTTCC
	RsaA DwR Sau-6041 DwR Sau-6053 DwF Teg116 UpF RNAIII DwR	AAGCTTGGTCTCATCTCAAATCACGTCTTATGTATACGG GATATCGGATCCGAGACCCTCTTTTGCTGTTTTATCAACTTTTTC ACCCCACAACCTAGGTATATTTTATTTAGCATAGGTCTTTTTGTTTG GAATTCGAGACCGCTAGCGCAAATCACTGCGTCATTTCCA GATATCGGATCCGAGACCCTTTTTGGTACTTCAACTTCATCCA
	Sau-6053 DwR Teg116 UpR Sau-6528 UpF	GATATCGGATCCGAGACCCTGGGAAGTGCTCAGGCAATAC GCGTATGGACCTAGGTATATTCCTTGTCATTCGCTCATTT GAATTCGAGACCGCTAGCGCGAAATCTGCATCTTTCGTTTCA
	Sau60 UpF Sau-41 UpF Teg116 DwF Sau-6528 UpR Sau-19 UpF	AAGCTTGGTCTCGAATTCCAGTAGCAGTAGCAGGTGCAG GAATTCGAGACCGCTAGCGCTCAAGATGTCGCAGCTGAAT ACCCCACAACCTAGGTATATTGAAATTATATTTTACAATGCCCAAA GCGTATGGACCTAGGTATATTCAAAATCAACTGACCGATATTC GAATTCGAGACCGCTAGCGCCCGCATTTGATTTTCGATTC
	Sau60 UpR Sau-41 UpR Teg58 UpF Teg116 DwR Sau-6528 DwF Sau-19 UpR	AAGCTTGGTCTCACACAATTATATAACTATAACAGAATATCCATTTC GCGTATGGACCTAGGTATATCGTTCTTAGTGGGACATACGG GAATTCGAGACCGCTAGCGCTTGTAATTTTGGAGAATGTGATTG GATATCGGATCCGAGACCCTAACGTTCACTTGGTACACCTACAA ACCCCACAACCTAGGTATATTTTTGTGTTGTGGATTAAGATTCTA GCGTATGGACCTAGGTATATCACAAATCCCTTTATTTATTTGGAA
	Sau60 DwF Sau-41 DwF Teg58 UpR Sau-6528 DwR Sau-19 DwF	AAGCTTGGTCTCATCTCTGCCGTTTTCTTTTTGTCTTT ACCCCACAACCTAGGTATATGCCAGCGATGATACCCATTA GCGTATGGACCTAGGTATATTTGGATATAGCAAAAAGCCACA GATATCGGATCCGAGACCCTCACAACAAGCATCTGCAAAA ACCCCACAACCTAGGTATATGCTATTAAACTTCCGTTCTTTGAA
	Sau60 DwR Sau-41 DwR Teg58 DwF Sau-6569 UpF Sau-19 DwR	AAGCTTGGTCTCGGATCCTCGCTGTTTGCATTTGATTC GATATCGGATCCGAGACCCTACCGAAAAAGCCAATGACTG ACCCCACAACCTAGGTATATAAGCACGCCAATACGTTAGC GAATTCGAGACCGCTAGCGCTTTTTCAATTTGGATGAACACA GATATCGGATCCGAGACCCTGGGTGATAAAGGTACTTGGATAGTT
	Teg58 DwR Sau-6569 UpR Sau-6387 UpF	GATATCGGATCCGAGACCCTTCCAACTTAGCAAACAAAATGTAGA GCGTATGGACCTAGGTATATTCTTCGTACTTCGCCAGTGA GAATTCGAGACCGCTAGCGCCGTGACCTCGCTCTGCTAAT
	RsaD UpF Sau-6428 UpF Sau-6569 DwF Sau-6387 UpR RsaH UpF	GAATTCGAGACCGCTAGCGCTCATCGCATTTGTTATTAGTTTTG GAATTCGAGACCGCTAGCGCATGATTTCGCCGAAGTGTTT ACCCCACAACCTAGGTATATGGTTCAAGCTACGCATTTTCA GCGTATGGACCTAGGTATATGATTGCACTAAACATGCATGAGA GAATTCGAGACCGCTAGCGCACGGACCACTAGCTGACTCG
	RsaD UpR Sau-6428 UpR Teg60 UpF Sau-6569 DwR Sau-6387 DwF RsaH UpR	GCGTATGGACCTAGGTATATTCATTTCCCATAAAAGCCAAG GCGTATGGACCTAGGTATATACACATTATATTAATCATCATTTTGTTTC GAATTCGAGACCGCTAGCGCCAATGCCTATCTTTGCACCA GATATCGGATCCGAGACCCTCAATACGGCATCTTCATTTCTG ACCCCACAACCTAGGTATATATTAATCACTTGAACGCGCAAT GCGTATGGACCTAGGTATATTGTATAACCTTTGAACAACAATAATGA
	RsaD DwF Sau-6428 DwF Teg60 UpR Sau-6387 DwR RsaH DwF	ACCCCACAACCTAGGTATATTAAAGGGGATGGTTTCGTGA ACCCCACAACCTAGGTATATAAACGTTTGCTTTTTGTGTGA GCGTATGGACCTAGGTATATAATTAAACACCGTTATTTTTCCTTTG GATATCGGATCCGAGACCCTAAAAACGGCAAATGACAGTAAAA ACCCCACAACCTAGGTATATAAATGAATCCGATTTACGAGTGA
	RsaD DwR Sau-6428 DwR Teg60 DwF Sau-6851 UpF RsaH DwR	GATATCGGATCCGAGACCCTCCTCTTCCAATTTGCTCGTC GATATCGGATCCGAGACCCTATCTCATCGCCGAAAAACTC ACCCCACAACCTAGGTATATTCATATTAAATCAAAGAGGCATTG GAATTCGAGACCGCTAGCGCTTTCTTCAACAATCGTGACACC GATATCGGATCCGAGACCCTCTTGTGGTTTTGCTTGCTGA
	Teg60 DwR Sau-6851 UpR Sau-6353 UpF New RsaH UpR	GATATCGGATCCGAGACCCTCTATTTGGATTTTATGCCTTGTGG GCGTATGGACCTAGGTATATGCTTTATCCGAGTTTAAAATGTTG GAATTCGAGACCGCTAGCGCCATGGGATCCGAGTAAATCC GCGTATGGACCTAGGTATATCCTTTATTATAACTTATATCATTTTTATTA
	New RsaD UpF Sau-6836 UpF Sau-6851 DwF Sau-6353 UpR RsaH DwF	GAATTCGAGACCGCTAGCGCGGAGAACTGGTACTAACGGC GAATTCGAGACCGCTAGCGCTTGTTGGTGCTAACTGCTTTG ACCCCACAACCTAGGTATATCCATTTCGATTTGTGCTATGA GCGTATGGACCTAGGTATATTAGCGAATTGTACATAAACAACAGC ACCCCACAACCTAGGTATATCTTATTCCCATTATACATCAATTTAAAGCA
	New RsaD UpR Sau-6836 UpR RsaB UpF Sau-6851 DwR Sau-6353 DwF	GCGTATGGACCTAGGTATATGCTTCAATTTCGGTAACTTTAAA GCGTATGGACCTAGGTATATTTTAATTAAGGTGAAGTGAATTAGCAA GAATTCGAGACCGCTAGCGCTTTGTTTCTTCTCCATCATCAA GATATCGGATCCGAGACCCTTTTTTCATTCTCCAATTATCTGTTT ACCCCACAACCTAGGTATATAAGCAAACTTCTGCCACTTCA
	New RsaD DwF Sau-6836 DwF RsaB UpR Sau-6353 DwR Ssr42 UpF	ACCCCACAACCTAGGTATATTGTGAGTGATATTTATTAGGGAAAGCT ACCCCACAACCTAGGTATATTGGGGCAACACTTTATTTGA GCGTATGGACCTAGGTATATGCGCTACAATTAACACTAATAATTG GATATCGGATCCGAGACCCTTGTTGAGACCATATTTAACATCTAACG GAATTCGAGACCGCTAGCGCTTGTCCCCCAGTAGAAAACG
	Sau-6836 DwR RsaB DwF Sau-11 UpF Ssr42 UpR	GATATCGGATCCGAGACCCTAATTCAAGACGCTCTGTATTTGA ACCCCACAACCTAGGTATATATTCATTGCATCGCTTTCCT GAATTCGAGACCGCTAGCGCAAATTTTACGTTGACCACTTGGA GCGTATGGACCTAGGTATATGTTTCAATCTATCTCTTTCTTTTTGTG
	RsaOG UpF RsaB DwR Sau-11 UpR RsaE UpF Ssr42 DwF	GAATTCGAGACCGCTAGCGCAATTGACCTTTTGCCACTCG GATATCGGATCCGAGACCCTTGATACCGATGCAGAAGTAGAA GCGTATGGACCTAGGTATATATATTGTGAACGCATAACTTTCC GAATTCGAGACCGCTAGCGCTCGTTGGGTCGATGTCTATG ACCCCACAACCTAGGTATATGCGCAATGCATAAAAACAAG
	RsaOG UpR Teg147 UpF Sau-11 DwF RsaE UpR Ssr42 DwR	GCGTATGGACCTAGGTATATGCATAAAATGAAGAAGTCTTCAGTTG GAATTCGAGACCGCTAGCGCTCTTGATGATTGAAGGGTCCA ACCCCACAACCTAGGTATATTTCATGAAATTTCGTTTAATTCG GCGTATGGACCTAGGTATATCAATCTGTTCATAATGTAAGCGAATA GATATCGGATCCGAGACCCTTTCATACTCAAATATCGAACAAAAAGA
	RsaOG DwF Teg147 UpR Sau-69 UpF Sau-11 DwR RsaE DwF	ACCCCACAACCTAGGTATATCACAATCTTTTTTAAAATGTAAGCG GCGTATGGACCTAGGTATATTTCGGTGTTGATTGGCATTA GAATTCGAGACCGCTAGCGCTTGTTCTGCATTCTACTTCTACGC GATATCGGATCCGAGACCCTAATGAGACCAGTGAAGAGTGAAA ACCCCACAACCTAGGTATATAAAAGACCTCGTTACATTTATGGTG
	RsaOG DwR Teg147 DwF Sau-69 UpR RsaE DwR Teg155 UpF	GATATCGGATCCGAGACCCTCAATTTCGAGTTCGGCAGTT ACCCCACAACCTAGGTATATGGAAACAGAGGCAACGCTAC GCGTATGGACCTAGGTATATCACCTTGCTATAATTATTTTGTTATAAATG GATATCGGATCCGAGACCCTCGAAATTTATTCATTTTTCGATCC GAATTCGAGACCGCTAGCGCTTCTCACTCAAGAGTTAAAGCAACA
	Teg147 DwR Sau-69 DwF Sau-27 UpF Teg155 UpR	GATATCGGATCCGAGACCCTGAGGCATCAGGCACAGAAAT ACCCCACAACCTAGGTATATCATGGGTTATTGATTGGTGAT GAATTCGAGACCGCTAGCGCGATGGACGTATTCATCCAGGT GCGTATGGACCTAGGTATATTGATTGCTTATTTATTTTATCAAGAGG
	RsaG UpF Sau-69 DwR Sau-27 UpR Teg130 UpF Teg155 DwF	GAATTCGAGACCGCTAGCGCAGGATGGAATCGTGCTGAAG GATATCGGATCCGAGACCCTCAACCTCTGATACTTCACCATCTT GCGTATGGACCTAGGTATATGGGAGACAAAAATTATTTCGCATA GAATTCGAGACCGCTAGCGCTATTTACCGCGTTCATGTGG ACCCCACAACCTAGGTATATTCGTGTTCCAATTTTACTGAGTATC
	RsaG UpR RsaOI UpF Sau-27 DwF Teg130 UpR Teg155 DwR	GCGTATGGACCTAGGTATATTTGCAATAGATTGGCGATACTTT GAATTCGAGACCGCTAGCGCTGGTAACTGCATATTTACCAACC ACCCCACAACCTAGGTATATATAAAGATGATTGGTTTTCTATCCA GCGTATGGACCTAGGTATATCGAGCTAGGGATACTCGAAAA GATATCGGATCCGAGACCCTCGCGATTGAAGATCATTTTG

*

Table S5 : Primers with experiment specifiers used for deep sequencing Name Sequence

 S5

	Primer 17-F Primer 34-F	GAAGCATATACCTAGGTCCATACGCAGCTATGCAAT AAGCCATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 17-R Primer 34-R	AAGTCATATACCTAGGTTGTGGGGTACAGCAATGAC CGTATATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 1-F Primer 18-F Primer 35-F	AAACAATATACCTAGGTCCATACGCAGCTATGCAAT GAGCAATATACCTAGGTCCATACGCAGCTATGCAAT ATTCCATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 1-R Primer 18-R Primer 35-R	GCATTATATACCTAGGTTGTGGGGTACAGCAATGAC GTATCATATACCTAGGTTGTGGGGTACAGCAATGAC CCACTATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 2-F Primer 19-F Primer 36-F	AAGAGATATACCTAGGTCCATACGCAGCTATGCAAT GGATGATATACCTAGGTCCATACGCAGCTATGCAAT ACTAAATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 2-R Primer 19-R Primer 36-R	ATGTTATATACCTAGGTTGTGGGGTACAGCAATGAC ACACCATATACCTAGGTTGTGGGGTACAGCAATGAC ACAGTATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 3-F Primer 20-F Primer 37-F	ATAGCATATACCTAGGTCCATACGCAGCTATGCAAT GGCAGATATACCTAGGTCCATACGCAGCTATGCAAT ACGTGATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 3-R Primer 20-R Primer 37-R	TACATATATACCTAGGTTGTGGGGTACAGCAATGAC TTCCCATATACCTAGGTTGTGGGGTACAGCAATGAC GGGGTATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 4-F Primer 21-F Primer 38-F	ATCACATATACCTAGGTCCATACGCAGCTATGCAAT GTACCATATACCTAGGTCCATACGCAGCTATGCAAT TATCCATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 4-R Primer 21-R Primer 38-R	TCAATATATACCTAGGTTGTGGGGTACAGCAATGAC CAGACATATACCTAGGTTGTGGGGTACAGCAATGAC GGTCAATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 5-F Primer 22-F Primer 39-F	AGTCAATATACCTAGGTCCATACGCAGCTATGCAAT GTGAGATATACCTAGGTCCATACGCAGCTATGCAAT CAAGATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 5-R Primer 22-R Primer 39-R	GTCCTATATACCTAGGTTGTGGGGTACAGCAATGAC TGAACATATACCTAGGTTGTGGGGTACAGCAATGAC GCACAATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 6-F Primer 23-F Primer 40-F	AGCTTATATACCTAGGTCCATACGCAGCTATGCAAT GCAAAATATACCTAGGTCCATACGCAGCTATGCAAT TCGCGATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 6-R Primer 23-R Primer 40-R	TCGCTATATACCTAGGTTGTGGGGTACAGCAATGAC ATGGCATATACCTAGGTTGTGGGGTACAGCAATGAC AGGGAATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 7-F Primer 24-F Primer 41-F	ACACTATATACCTAGGTCCATACGCAGCTATGCAAT GCGTTATATACCTAGGTCCATACGCAGCTATGCAAT GATGAATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 7-R Primer 24-R Primer 41-R	CGAGTATATACCTAGGTTGTGGGGTACAGCAATGAC GGAGCATATACCTAGGTTGTGGGGTACAGCAATGAC GTTCCATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 8-F Primer 25-F Primer 42-F	ACGCAATATACCTAGGTCCATACGCAGCTATGCAAT CAAAAATATACCTAGGTCCATACGCAGCTATGCAAT GTAGTATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 8-R Primer 25-R Primer 42-R	CCGGTATATACCTAGGTTGTGGGGTACAGCAATGAC AATTGATATACCTAGGTTGTGGGGTACAGCAATGAC TATACATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 9-F Primer 26-F Primer 43-F	TAAGAATATACCTAGGTCCATACGCAGCTATGCAAT CACCCATATACCTAGGTCCATACGCAGCTATGCAAT GTCAAATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 9-R Primer 26-R Primer 43-R	CTATAATATACCTAGGTTGTGGGGTACAGCAATGAC AGATGATATACCTAGGTTGTGGGGTACAGCAATGAC AGGACATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 10-F Primer 27-F Primer 44-F	TAGCTATATACCTAGGTCCATACGCAGCTATGCAAT CTAAGATATACCTAGGTCCATACGCAGCTATGCAAT GTGGAATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 10-R Primer 27-R Primer 44-R	CAGTAATATACCTAGGTTGTGGGGTACAGCAATGAC TCGAGATATACCTAGGTTGTGGGGTACAGCAATGAC ATAACATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 11-F Primer 28-F Primer 45-F	TTACTATATACCTAGGTCCATACGCAGCTATGCAAT CTGCCATATACCTAGGTCCATACGCAGCTATGCAAT GTTTCATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 11-R Primer 28-R Primer 45-R	CCTAAATATACCTAGGTTGTGGGGTACAGCAATGAC CCAAGATATACCTAGGTTGTGGGGTACAGCAATGAC TAGGCATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 12-F Primer 29-F Primer 46-F	TGTTTATATACCTAGGTCCATACGCAGCTATGCAAT CGAATATATACCTAGGTCCATACGCAGCTATGCAAT GCTGGATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 12-R Primer 29-R Primer 46-R	GGGAAATATACCTAGGTTGTGGGGTACAGCAATGAC GATCGATATACCTAGGTTGTGGGGTACAGCAATGAC GAATGATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 13-F Primer 30-F Primer 47-F	TGAAGATATACCTAGGTCCATACGCAGCTATGCAAT CGCACATATACCTAGGTCCATACGCAGCTATGCAAT CTCTCATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 13-R Primer 30-R Primer 47-R	TATCAATATACCTAGGTTGTGGGGTACAGCAATGAC AACCGATATACCTAGGTTGTGGGGTACAGCAATGAC ACCAGATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 14-F Primer 31-F Primer 48-F	TGGATATATACCTAGGTCCATACGCAGCTATGCAAT CGTTGATATACCTAGGTCCATACGCAGCTATGCAAT CGAGGATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 14-R Primer 31-R Primer 48-R	CGACAATATACCTAGGTTGTGGGGTACAGCAATGAC TGGGGATATACCTAGGTTGTGGGGTACAGCAATGAC ACGCGATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 15-F Primer 15-R Primer 32-F Primer 32-R * Grey highlighted sequences are tag specific. TCATTATATACCTAGGTCCATACGCAGCTATGCAAT GTCGAATATACCTAGGTTGTGGGGTACAGCAATGAC CCCTTATATACCTAGGTCCATACGCAGCTATGCAAT CTCGGATATACCTAGGTTGTGGGGTACAGCAATGAC
	Primer 16-F Primer 33-F	TCGGAATATACCTAGGTCCATACGCAGCTATGCAAT AAATCATATACCTAGGTCCATACGCAGCTATGCAAT
	Primer 16-R Primer 33-R	CTGGAATATACCTAGGTTGTGGGGTACAGCAATGAC AACTTATATACCTAGGTTGTGGGGTACAGCAATGAC

Table S6 : Primers to generate cwrA/rsaOV complementing plasmids Name* Sequence

 S6

Table 1 .

 1 Relative amounts of putative sRNA-targets in strains lacking or overexpressing sRNAs, determined by qRT-PCR.

		srna/WT 1 +aTc/-aTc 2
	RNAIII	0.00	358.7 ±25
	SAOUHSC_00074 (sirA)	1.07 ± 0.63 0.62 ± 0.05
	SAOUHSC_00192 (coa)	1.14 ± 0.19 0.23 ± 0.02
	SAOUHSC_00652 (fhuC)	1.07 ± 0.12 0.59 ± 0.01
	SAOUHSC_00826	1.94 ± 0.28 1.03 ± 0.05
	SAOUHSC_01110 (fbp)	0.95 ± 0.04 0.14 ± 0.01
	SAOUHSC_01653 (sodA)	0.97 ± 0.02 0.60 ± 0.05
	SAOUHSC_02554 (fhuD2)	1.07 ± 0.10 0.38 ± 0.01
	SAOUHSC_02589 (rpiR)	1.04 ± 0.07 2.47 ± 0.05
	SAOUHSC_02670 (hsp gene) 0.99 ± 0.04 1.98 ± 0.28
	SAOUHSC_02706 (sbi)	1.25 ± 0.09 0.47 ± 0.01
	SAOUHSC_02872	0.51 ± 0.04 1.42 ± 0.21
	RsaA	0.00	155.9 ± 14.1
	SAOUHSC_00694 (mgrA)	0.88 ± 0.08 1.86 ± 0.26
	SAOUHSC_02576 (ssaA)	4.10 ± 1.99 1.17 ± 0.11
	SAOUHSC_02855 (ssaA-like) 1.28 ± 1.01 3.39 ±0.22
	SAOUHSC_02883 (ssaA-like) 1.22 ± 0.84 1.77 ±0.19
	RsaE	0.00	359.8 ± 14.6
	SAOUHSC_00894 (rocD)	2.42 ± 2.66 0.46 ± 0.06

Table S2 .

 S2 qRT-PCR results.

	≥ 3.00
	1 -

Variation of gene expression in sRNA strains relative to the wild type strain (wt) using the four reference genes. 2 -Variation of gene expression in sRNA pRMC2- sRNA in the induced state (+aTc) relative to the same strains non-induced (-aTc) using the four reference genes.

  Variation of gene expression using the four reference genes (ftsZ, recA, gyrB and glyA): 1 -in ΔsRNA strains relative to the wild type strain (ΔsRNA is either ΔRNAIII, ΔrsaA, ΔrsaE or ΔrsaH); 2in ΔsRNA pRMC2-sRNA strain (sRNA is either RNAIII, rsaA, rsaE or rsaH) in the presence of aTc (induced state, column +aTc) relative to the same strains prior aTc addition (non-induced state, column -aTc). The values correspond to the three replicates from biological independent RNA samples.

	SAOUHSC_01081 (conserved protein) SAOUHSC_02571 (ssaA-like, CHAP domain) SAOUHSC_00005 (gyrB)	0.92 0.81 1.01	1.03 1.24 1.06	1.06 1.00 0.94	0.88 0.66 1.09	0.85 0.69 0.99	0.85 0.98 1.10	1.04 0.81 0.95	0.97 0.93 1.01	1.00 1.33 1.05	1.21 0.82 0.98	1.14 0.74 0.85	1.09 0.83 0.92
	SAOUHSC_01110 (fbp, fibrinogen-binding prot.) SAOUHSC_02576 (ssaA, CHAP domain) SAOUHSC_02354 (glyA)	0.92 0.89 0.96	1.00 0.54 1.16	1.09 2.09 0.90	0.99 2.38 1.07	0.92 3.65 1.16	0.95 6.28 1.49	0.97 0.90 1.03	1.03 0.97 0.96	1.00 1.14 1.01	0.15 1.12 0.98	0.14 1.09 0.91	0.14 1.30 0.85
	SAOUHSC_01592 (fur, transcriptional regulator) SAOUHSC_02855 (ssaA-like, CHAP domain) RsaH	0.96 0.88 1.08	0.92 0.79 1.38	1.13 1.44 0.67	0.92 0.63 0.00	0.90 0.76 0.00	0.90 2.44 0.00	1.03 0.98 1.12	1.01 0.84 1.00	0.96 1.21 0.89 229.90 248.85 205.60 1.31 1.25 1.15 3.55 3.14 3.48
	SAOUHSC_01653 (sodA, Mn-dependent SOD) SAOUHSC_02883 (ssaA-like, CHAP domain) SAOUHSC_00067 (L-lactate permease)	0.84 0.98 0.83	0.94 0.81 1.14	1.27 1.26 1.05	0.99 0.80 0.96	0.96 0.67 1.78	0.96 2.19 1.96	1.03 1.10 1.04	0.95 0.97 1.12	1.03 0.94 0.86	0.66 1.99 1.27	0.60 1.69 1.55	0.55 1.64 1.34
	≥ 1.50 < 1.5 or > 0.67 ≤ 0.67 ≤ 0.33 4 references ftsZ/recA/gyrB/glyA RNAIII SAOUHSC_01150 (ftsZ) SAOUHSC_01262 (recA) SAOUHSC_00005 (gyrB) SAOUHSC_02354 (glyA) RNAIII SAOUHSC_00070 (sarH1; Sar-like protein) SAOUHSC_00074 (sirA, lipoprotein receptor) SAOUHSC_00192 (coa, coagulase) SAOUHSC_00257 (esxA, secreted antigen) SAOUHSC_00362 (conserved protein) SAOUHSC_00539 (conserved protein) SAOUHSC_00652 (fhuC, iron transport) SAOUHSC_00826 (conserved protein) SAOUHSC_00715 (saeR, response regulator) SAOUHSC_00935 (mecA, adapter protein) SAOUHSC_01060 (conserved protein) SAOUHSC_02019 (lytN, N-acetylmuramoyl-L-alanine amidase) SAOUHSC_02419 (conserved protein) SAOUHSC_02528 (conserved protein) SAOUHSC_02554 (fhuD2, iron transport) SAOUHSC_02568 (conserved protein) SAOUHSC_02589 (rpiR, transcriptional regulator) SAOUHSC_02660 (CorA-like transporter) SAOUHSC_02670 (heat shock protein) SAOUHSC_02706 (sbi, igG-binding protein) SAOUHSC_02872 (conserved protein) SAOUHSC_02931 (conserved protein) RsaA 4 references ftsZ/recA/gyrB/glyA SAOUHSC_01150 (ftsZ) SAOUHSC_01262 (recA) SAOUHSC_00005 (gyrB) SAOUHSC_02354 (glyA) RsaA SAOUHSC_00640 (tagA, teichoic acid bios.) SAOUHSC_00694 (mgrA, norR, transcript. reg.) SAOUHSC_01211 (rplS) SAOUHSC_01238 (cdsA, lipid metabolism) IGR-1418475 SAOUHSC_01262 (recA) SAOUHSC_01150 (ftsZ) 4 references ftsZ/recA/gyrB/glyA RsaH RsaE SAOUHSC_00206 (lctE, L-lactate DH) 4 references ftsZ/recA/gyrB/glyA SAOUHSC_02648 (lctP, L-lactate permease) SAOUHSC_01150 (ftsZ) SAOUHSC_01260 (pgsA) SAOUHSC_01262 (recA) SAOUHSC_00785 (trxB, thioredoxin reductase) SAOUHSC_00005 (gyrB) SAOUHSC_01732 (cymR, transcriptional factor) SAOUHSC_02354 (glyA) SAOUHSC_01879 (rot, repressor of toxins) RsaE SAOUHSC_02108 (ftnA, ferritin) SAOUHSC_00819 (cspC, cold-shock protein) SAOUHSC_02972 (isaB, immunodominant ag. B) SAOUHSC_00875 (pyridine oxidoreductase) SAOUHSC_00681 (MFS protein) SAOUHSC_00894 (rocD, ornithine aminotransf.) SAOUHSC_00465 (veg, conserved protein) SAOUHSC_01016 (purN, purine and folate met.) SAOUHSC_00863 (conserved protein) SAOUHSC_01138 (acetyltransferase) SAOUHSC_01044 (conserved protein) SAOUHSC_01287 (glnA, glutamine synthetase) SAOUHSC_01062 (conserved protein) SAOUHSC_01542 (SNF2-related protein) SAOUHSC_01382 (conserved trans-menb. protein) SAOUHSC_02409 (rocF, arginase) SAOUHSC_01721 (conserved protein) RsaOG (Teg24, RsaI) sRNA SAOUHSC_01918 (conserved protein) SAOUHSC_02836 (acetyltransferase ) SAOUHSC_02303 (MazF-like protein) RsaX25/Teg141 sRNA SAOUHSC_02424 (conserved protein) SAOUHSC_03001 (icaR, transcriptional regulator) SAOUHSC_02555 (acyl-CoA DH-like protein) SAOUHSC_02779 (conserved protein)	1.00 0.92 1.05 1.13 0.91 1.13 1.11 1.52 1.10 0.99 1.13 1.07 1.02 0.61 1.06 0.99 1.05 0.94 0.91 1.11 0.96 0.81 1.01 1.12 0.90 1.03 1.01 0.81 1.00 0.92 1.12 1.01 0.96 0.58 0.97 0.92 0.92 1.14 0.93 1.12 0.92 1.00 1.44 1.00 1.31 0.92 0.88 1.12 0.94 1.01 1.32 0.96 0.87 0.96 0.84 1.40 1.01 0.97 1.07 0.91 1.10 0.65 0.98 0.83 0.96 0.87 0.87 0.92 0.98 1.11 0.95 1.15 1.13 0.98 0.97 0.72 1.09 1.12 1.13 0.92	wt 1.00 0.98 1.01 0.99 1.02 1.02 1.04 1.04 1.02 1.04 1.00 1.00 1.03 1.10 1.04 1.02 1.00 0.98 1.03 0.99 1.03 0.91 0.99 0.99 1.04 1.01 1.02 0.99 wt 1.00 1.02 0.80 1.06 1.16 3.03 0.88 1.04 0.98 0.74 1.13 0.80 1.02 1.00 wt wt 1.13 1.00 1.41 1.02 1.08 0.80 1.01 1.06 0.72 1.16 1.25 1.43 1.23 0.72 1.32 1.14 1.07 2.04 1.08 0.94 0.62 1.39 0.97 0.94 1.21 1.29 0.89 1.31 1.12 2.62 1.10 0.86 1.16 1.18 1.01 0.86 1.37 1.03	1.00 1.10 0.94 0.90 1.07 0.86 0.87 0.63 0.89 0.97 0.88 0.93 0.96 1.48 0.91 0.99 0.95 1.08 1.06 0.91 1.01 1.36 0.99 0.90 1.06 0.96 0.97 1.25 1.00 1.07 1.12 0.94 0.90 0.57 1.17 1.05 1.11 1.18 0.96 1.12 1.07 1.00 0.62 1.00 0.54 1.07 1.05 1.12 1.05 0.94 1.05 0.90 0.93 0.73 0.97 0.99 0.75 0.90 0.88 0.54 0.84 1.64 1.64 0.86 1.07 1.23 0.95 0.85 1.15 0.69 0.94 0.33 0.80 1.18 0.90 1.19 0.91 1.04 0.65 1.05	1.00 0.98 0.99 0.93 1.11 0.00 0.67 0.66 1.16 1.03 0.82 0.93 1.00 1.64 0.90 1.02 0.72 1.24 0.89 0.83 1.08 0.92 0.97 1.01 1.02 1.35 0.55 1.26 1.00 1.09 0.90 0.96 1.05 0.00 0.95 0.97 0.89 1.08 1.09 0.91 0.93 1.00 1.39 1.00 1.62 0.64 0.83 1.08 0.92 1.42 1.56 1.02 0.78 0.00 0.82 0.97 0.77 0.80 1.00 0.84 0.86 1.18 0.72 2.48 0.89 0.56 0.92 1.38 0.90 2.89 1.00 0.47 1.29 0.66 0.91 0.62 1.05 1.30 1.17 0.99	RNAIII 1.00 1.00 1.02 0.89 1.10 0.00 0.84 0.76 0.94 0.98 0.80 0.87 1.00 1.97 0.86 0.94 0.76 1.17 0.90 0.79 0.97 0.88 1.05 0.96 0.94 1.17 0.51 1.50 rsaA 1.00 0.91 0.87 1.16 1.09 0.00 1.06 0.86 0.77 0.90 0.85 0.72 1.20 1.00 rsaH rsaE 0.52 1.00 1.24 0.80 1.20 0.82 1.28 1.20 0.67 1.27 1.48 0.00 1.22 0.47 1.21 1.33 1.38 5.49 1.16 0.95 0.72 5.04 0.97 0.80 1.39 1.21 0.76 5.98 1.07 2.20 1.38 0.81 1.01 0.68 1.12 0.77 1.14 1.28	1.00 0.90 1.12 0.94 1.06 0.00 0.89 1.80 1.32 1.10 0.85 1.02 1.20 2.21 0.87 1.03 0.76 1.15 0.94 0.98 1.17 0.86 1.11 0.97 1.00 1.23 0.47 2.27 1.00 0.99 1.00 1.02 0.99 0.00 1.15 0.82 0.96 1.34 0.89 0.79 0.77 1.00 1.17 1.00 1.77 0.95 0.75 1.02 0.84 0.99 0.84 1.04 0.99 0.00 1.18 0.76 1.21 0.92 1.17 0.93 1.24 1.15 0.72 2.06 1.20 1.31 0.78 0.85 0.58 2.65 0.92 0.20 1.70 1.08 0.84 0.67 1.31 1.15 0.73 1.20	1.00 1.01 0.98 0.98 1.03 0.99 0.99 0.88 0.91 0.94 1.01 0.97 1.02 0.99 0.98 0.92 0.98 1.11 1.04 0.95 1.02 0.97 0.96 0.99 1.06 1.04 1.04 0.95 1.00 0.87 1.03 1.03 1.08 1.06 1.00 0.92 0.93 0.82 0.86 1.00 1.02 1.00 1.39 1.00 1.63 0.97 1.07 1.01 1.03 1.01 1.05 1.01 1.13 0.89 1.05 0.98 1.04 0.94 0.87 1.00 1.19 0.98 1.05 0.97 1.04 1.06 1.15 0.99 1.00 1.00 0.96 0.91 0.96 1.00 1.07 0.98 1.06 0.94 1.00 1.05	-aTc 1.00 0.98 1.04 1.00 0.99 1.02 1.01 1.31 1.08 1.03 0.99 0.99 1.02 0.94 1.04 1.01 0.99 1.00 1.03 0.99 0.95 1.02 1.07 1.03 1.00 1.02 1.06 1.03 -aTc 1.00 0.94 0.98 1.06 1.02 0.95 1.02 0.84 0.86 1.05 0.93 1.03 1.00 1.00 -aTc -aTc 0.43 1.00 0.38 1.00 1.10 0.97 1.01 1.03 0.97 1.00 0.87 1.13 1.02 1.05 0.92 0.91 1.05 0.99 0.92 1.03 1.07 1.03 0.98 1.02 0.97 1.13 1.03 1.01 1.04 1.08 0.89 1.04 0.97 0.85 0.95 1.13 1.00 1.06	+ aTc 1.00 1.01 1.03 0.94 1.01 0.99 365.41 380.04 330.79 1.00 1.00 1.00 1.01 0.98 1.00 0.98 1.07 1.04 1.03 0.94 0.98 0.99 1.01 0.98 1.00 1.09 1.15 1.02 0.86 0.60 0.68 0.60 1.01 0.24 0.21 0.24 1.04 1.00 1.07 1.18 1.01 1.02 1.08 1.07 1.05 1.09 1.12 1.09 0.96 0.59 0.58 0.58 1.07 1.08 1.00 1.01 0.98 0.85 0.88 0.94 1.08 0.95 0.97 1.08 1.02 0.86 0.84 0.79 0.90 1.16 1.12 1.08 0.93 1.46 1.39 1.24 1.06 0.82 0.87 0.87 1.04 0.37 0.38 0.38 1.01 0.92 0.87 0.77 0.98 2.51 2.42 2.48 0.98 1.01 1.03 1.02 0.94 2.20 2.07 1.66 0.94 0.46 0.47 0.48 0.91 1.63 1.42 1.20 1.03 1.17 1.16 1.10 + aTc 1.00 1.00 1.00 1.00 1.21 1.11 0.88 1.07 0.99 1.21 1.24 1.17 0.92 0.84 0.96 0.85 0.91 0.88 0.96 0.94 1.00 162.17 139.79 165.94 0.98 1.50 1.41 1.30 2.13 1.61 1.25 1.36 1.00 1.17 1.23 1.21 1.26 1.19 1.06 1.27 0.97 1.15 1.21 1.14 1.29 0.98 0.91 1.07 1.13 1.34 1.00 1.00 1.00 1.00 1.85 + aTc 1.44 1.68 0.44 0.20 0.18 + aTc 1.00 1.00 1.00 1.60 0.27 0.12 0.13 1.00 1.03 1.04 1.01 0.85 0.94 0.99 0.88 1.22 1.02 1.07 1.09 0.96 0.98 0.97 0.94 1.02 0.96 1.01 1.03 0.98 0.90 0.80 0.83 0.98 0.99 0.89 0.88 1.01 0.67 0.81 0.67 0.82 0.93 2.15 2.28 1.85 1.00 355.81 347.67 376.07 0.97 1.51 1.70 1.04 0.53 0.57 0.54 2.30 1.17 0.80 0.72 1.09 0.96 0.99 0.89 0.99 1.01 0.47 0.51 0.92 1.81 1.96 1.69 0.40 1.00 1.49 1.38 0.88 1.69 1.85 1.54 1.19 1.00 0.46 0.56 0.98 1.18 1.26 1.33 0.39 0.92 1.13 1.17 0.90 1.68 1.78 1.57 0.96 0.89 1.27 1.46 0.97 1.07 1.12 1.04 1.19 0.99 0.33 0.32 1.00 1.17 1.11 1.06 0.28 1.02 2.07 2.55 1.17 1.14 1.04 1.22 2.40 0.96 2.06 2.05 0.97 1.43 1.26 1.25 2.02 1.21 1.50 1.17 0.98 2.17 1.77 1.65 1.82 0.94 0.79 0.72 1.01 1.35 1.36 1.37 0.72 0.90 0.80 0.97 0.89

Table S3 .

 S3 Oligonucleotides and strains.

	RsaH_206_Right pRMC2_RsaA_R 0452-SAO02576-F1 0481-*2377226-R1 SAPhB162 SAOUHSC_00894 (rocD) SAOUHSC_02773 SAOUHSC_00835 SAOUHSC_02351	SAOUHSC_00206 detection rsaA ampl. for pRMC2 cloning Quant. of the corresponding gene Quant. of the corresponding gene as HG003 DrsaE::tag45 135 125 127 200	35 25 27 100	GCTAATCCCATTGCAACACC TCAGATCTGTTAACGGTACCCCGTATACATAAGACGTGATTTGG TCATGCAGATGCTGCTGAAAAT GTCACGTGCTAGCCGACAAA HG003 + pMAD*rsaA::tag45 857683..857817 23.124 2550063..2550187 10.47 809475..809601 9 2174538..2174339	118-135 6 --53 5 -14 56 --62
	RNAIII_2589_left pRMC2_RsaH_F 0453-SAO02576-R1 0482-SAO02836-F1 SAPhB163 SAOUHSC_01016 (purN) RsaH SAOUHSC_02150 SAOUHSC_02317 Oligonucleotide Name 1) Synthetic RNAs production using T7 promoter: rpiR detection rsaH ampl. for pRMC2 cloning Quant. of the corresponding gene Quant. of the corresponding gene as HG003 DrsaH::tag49 200 Size 124 200 Description 1166 T7-rnaIII forward 1167 rnaIII reverse SA79 T7-rsaA forward SA80 rsaA reverse SA81 T7-rsaE forward SA82 rsaE reverse SA83 T7-rsaH forward SA84 rsaH reverse 2) Northern blots: RsaA_694_left mgrA detection RsaA_694_right mgrA detection RsaA_2855_left SAOUHSC_02855 detection RsaA_2855_right SAOUHSC_02855 detection RsaE_2409_left rocF detection RsaE_2409_Right rocF detection RsaE_2836_left SAOUHSC_02809 detection RsaE_2836_Right SAOUHSC_02809 detection RsaE_1138_left SAOUHSC_01138 detection RsaE_1138_Right SAOUHSC_01138 detection RsaH_2972_left isaB detection RsaH_2972_Right isaB detection RsaH_2108_left ftnA detection RsaH_2108_Right ftnA detection RsaH_206_left SAOUHSC_00206 detection RNAIII_2589_Right rpiR detection RNAIII_2554_left fhuD2 detection RNAIII_2554_Right fhuD2 detection RNAIII_2706_left sbi detection RNAIII_2706_Right sbi detection HU-45_left hu detection HU_46_Right hu detection 3) sRNA deletions: Up-RsaE-F rsaE upstream seq Up-RsaE-R rsaE upstream seq Down-RsaE-F rsaE downstream seq Down-RsaE-R rsaE downstream seq Up-RNAIII-F rnaIII upstream seq Up-RNAIII-R rnaIII upstream seq Down-RNAIII-F rnaIII downstream seq Down-RNAIII-R rnaIII downstream seq Up-RsaH-F rsaH upstream seq Up-RsaH-R rsaH upstream seq Down-RsaH-F rsaH downstream seq Down-RsaH-R rsaH downstream seq pMADOF_R (733) pMAD* amplification pMADOF_F (732) pMAD* amplification Tag primer2(736) Tag amplification Tag primer1(735) Tag amplification 4) pRMC2-sRNA constructions: pRMC2_RsaA_F rsaA ampl. for pRMC2 cloning pRMC2_RsaH_R rsaH ampl. for pRMC2 cloning pRMC2_RNAIII_F rnaIII ampl. for pRMC2 cloning pRMC2_RNAIII_R rnaIII ampl. for pRMC2 cloning pRMC2_F pRMC2 amplification pRMC2_R pRMC2 amplification 5) qRT-PCR experiments: 0616-SAOUHSC01150-F1r Quant. of the corresponding gene 0617-SAOUHSC01150-R1r Quant. of the corresponding gene 0622-SAOUHSC01262-F1r Quant. of the corresponding gene 0623-SAOUHSC01262-R1r Quant. of the corresponding gene 0628-SAOUHSC00005-F1r Quant. of the corresponding gene 0629-SAOUHSC00005-R1r Quant. of the corresponding gene 0642-SAOUHSC02354-F1r Quant. of the corresponding gene 0643-SAOUHSC02354-R1r Quant. of the corresponding gene 0438-SAO00640-F1 Quant. of the corresponding gene 0439-SAO00640-R1 Quant. of the corresponding gene 0440-SAO00694-F1 Quant. of the corresponding gene 0441-SAO00694-R1 Quant. of the corresponding gene 0442-SAO01211-F1 Quant. of the corresponding gene 0443-SAO01211-R1 Quant. of the corresponding gene 0444-SAO01238-F1 Quant. of the corresponding gene 0445-SAO01238-R1 Quant. of the corresponding gene 0446-*1418475-F1 Quant. of the corresponding gene 0447-*1418475-R1 Quant. of the corresponding gene 0450-SAO02571-F1 Quant. of the corresponding gene 0451-SAO02571-R1 Quant. of the corresponding gene 0454-SAO02671-F1 Quant. of the corresponding gene 0455-SAO02671-R1 Quant. of the corresponding gene 0456-SAO02684-F1 Quant. of the corresponding gene 0457-SAO02684-R1 Quant. of the corresponding gene 0458-SAO02855-F1 Quant. of the corresponding gene 0459-SAO02855-R1 Quant. of the corresponding gene 0460-SAO02883-F1 Quant. of the corresponding gene 0461-SAO02883-R1 Quant. of the corresponding gene 0462-RsaA-F1 Quant. of the corresponding gene 0463-RsaA-R1 Quant. of the corresponding gene 0464-SAO00819-F1 Quant. of the corresponding gene 0465-SAO00819-R1 Quant. of the corresponding gene 0466-SAO00875-F1 Quant. of the corresponding gene 0467-SAO00875-R1 Quant. of the corresponding gene 0468-SAO00894-F1 Quant. of the corresponding gene 0469-SAO00894-R1 Quant. of the corresponding gene 0470-SAO01016-F1 Quant. of the corresponding gene 0471-SAO01016-R1 Quant. of the corresponding gene 0472-SAO01138-F1 Quant. of the corresponding gene 0473-SAO01138-R1 Quant. of the corresponding gene 0474-SAO01287-F1 Quant. of the corresponding gene 0475-SAO01287-R1 Quant. of the corresponding gene 0476-SAO01542-F1 Quant. of the corresponding gene 0477-SAO01542-R1 Quant. of the corresponding gene 0478-SAO02409-F1 Quant. of the corresponding gene 0479-SAO02409-R1 Quant. of the corresponding gene 0480-*2377226-F1 Quant. of the corresponding gene 0483-SAO02836-R1 Quant. of the corresponding gene 0484-*2773602-F1 Quant. of the corresponding gene 0485-*2773602-R1 Quant. of the corresponding gene 0486-SAO03001-F1 Quant. of the corresponding gene 0487-SAO03001-R1 Quant. of the corresponding gene 0488-RsaE-F1 Quant. of the corresponding gene SAPhB302 as HG003 DrnaIII::tag47 SAPhB301 as HG003 DrsaA::tag1 pRMC2RsaA UTR size 100 24 100 SAOUHSC_01138 133 33 SAOUHSC_00067 324 224 SAOUHSC_00204 125 25 SAOUHSC_01181 198 98 SAPhB282 as HG003 DrsaE::tag45 pRMC2RsaE SAOUHSC_01287 (glnA) 171 71 SAOUHSC_00206 (lctE) 411 311 SAOUHSC_02875 200 100 SAOUHSC_01131 180 80 SAPhB283 as HG003 DrsaH::tag49 pRMC2RsaH SAOUHSC_01542 200 100 SAOUHSC_02648 (lctP) 224 124 SAOUHSC_01983 131 31 SAOUHSC_00942 200 100 SAPhB303 as HG003 DrnaIII::tag47 pRMC2RNAIII SAOUHSC_02409 (rocF) 123 23 SAOUHSC_01260 (pgsA)/SAOUHSC_01257 200 100 SAOUHSC_01282 123 24 rsaD 177 x RsaOG (Teg24, RsaI) sRNA 149 x SAOUHSC_00785 (trxB) 200 100 SAOUHSC_00613 319 219 SAOUHSC_00642 281 181 0489-RsaE-R1 Quant. of the corresponding gene SAOUHSC_02836 114 14 SAOUHSC_01732 (cymR) 200 100 SAOUHSC_01617 196 96 SAOUHSC_00501 154 54 0490-SAO00067-F1 Quant. of the corresponding gene RsaX25/Teg141 sRNA 307 x SAOUHSC_01879 (rot) 362 262 SAOUHSC_01164 455 355 SAOUHSC_00229 116 16 0491-SAO00067-R1 Quant. of the corresponding gene SAOUHSC_03001 (icaR) 172 72 SAOUHSC_02108 (ftnA) 142 42 SAOUHSC_01021 200 100 IGR_asSAOUHSC_A02856 200 x 0492-SAO00206-F1 Quant. of the corresponding gene SAOUHSC_00086 134 34 SAOUHSC_02972 (isaB) 139 39 SAOUHSC_01822 200 100 SAOUHSC_02625-AS02627 200 100 0493-SAO00206-R1 Quant. of the corresponding gene SAOUHSC_00299 200 100 SAOUHSC_00681/SAOUHSC_00679 200 100 Teg56 293 x SAOUHSC_00950 123 23 0494-SAO02648-F1 Quant. of the corresponding gene 0495-SAO02648-R1 Quant. of the corresponding gene 0496-SAO01260-F1 Quant. of the corresponding gene 0497-SAO01260-R1 Quant. of the corresponding gene 0498-SAO00785-F1 Quant. of the corresponding gene 0499-SAO00785-R1 Quant. of the corresponding gene 0500-SAO01732-F1 Quant. of the corresponding gene 0501-SAO01732-R1 Quant. of the corresponding gene 0502-SAO01879-F1 Quant. of the corresponding gene 0503-SAO01879-R1 Quant. of the corresponding gene 0504-SAO02108-F1 Quant. of the corresponding gene 0505-SAO02108-R1 Quant. of the corresponding gene 0506-SAO02972-F1 Quant. of the corresponding gene 0507-SAO02972-R1 Quant. of the corresponding gene 0508-SAO00681-F1 Quant. of the corresponding gene 0509-SAO00681-R1 Quant. of the corresponding gene SAOUHSC_02520 188 88 SAOUHSC_01208 218 118 SAOUHSC_02794 156 56 SAOUHSC_T00034 199 x SAOUHSC_01477 200 100 SAOUHSC_02848 231 131 SAOUHSC_T00055 76 x SAOUHSC_01846 113 13 SAOUHSC_02393 202 102 IGR_1821348 104 x SAOUHSC_02332 156 56 SAOUHSC_02604 169 69 SAOUHSC_01485 174 74 SAOUHSC_02540 200 100 SAOUHSC_00429 146 46 IGR_1274679 118 x SAOUHSC_00890 200 100 SAOUHSC_02867 205 105 IGR_1247676 91 x SAOUHSC_02779 145 45 SAOUHSC_02910 200 100 SAOUHSC_01320 163 63 SAOUHSC_02555 170 70 SAOUHSC_01278 200 100 sRNA Teg103 144 x SAOUHSC_02424 117 17 SAOUHSC_00792 208 108 SAOUHSC_T0006 166 x SAOUHSC_02303/ SAOUHSC_02304 200 100 SAOUHSC_02305 200 100 SAOUHSC_00932 200 100 SAOUHSC_01918 172 72 SAOUHSC_02399 542 442 SAOUHSC_00926 200 100 SAOUHSC_01721 200 100 RsaG 230 x SAOUHSC_00892 163 63 SAOUHSC_01382 239 139 SAOUHSC_01689 282 182 SAOUHSC_00730 200 100 SAOUHSC_01062 186 86 SAOUHSC_02585 129 29 SAOUHSC_00698 129 29 SAOUHSC_01044 200 100 SAOUHSC_01340 200 100 SAOUHSC_00561 129 29 SAOUHSC_00863 123 23 SAOUHSC_00141 200 100 SAOUHSC_00502 139 39 SAOUHSC_00465 (veg) 200 100 SAOUHSC_00971 109 9 SAOUHSC_00174 156 26	CATCAGTCATTCGATTCAGCA GATAGAGTATAATTAAAATAAGCGTACCTTCGATAACGAATAAACATCTC AACCGATTTCTCCGCCAACT TAGACGAACGTGTCGCATGG HG003 + pMAD*rsaA::tag49 986097..986296 Genome pos.: start..end Motif 1 Motif 2 Motif 3 2022495..2022618 8 2151662..2151463 Sequence (5' -> 3') TAATACGACTCACTATAGGGTAACTAGATCACAGAGATGTGATGG GCCGCGAGCTTGGGAGGG TAATACGACTCACTATAGGGAGTTAACCATTACAAAAATTGTATAGAGTAGC 32 --49 85-92 5 -13 IntaRNA AACAAAGTACACTTTGCTCATAGCA TAATACGACTCACTATAGGGATGAAATTAATCACATAACAAACATACCC ATAAAAAAACGTCGTGTCTGAATACA TAATACGACTCACTATAGGGTACCTTCGATAACGAATAAACATCTC AAATAAAAACGACCCGCACG CAATGCTCAAAGACAAGTTAATCG GCTGAAGCGACTTTGTCAGA GTCGAACAAACGCATCAATC GTTACGTGCTGCCTTTTTGC GCACCATCAACATTTGGACA GCGTTTCAAGCGGATCTAAA CCACAAACCATAGACGAACG GCAAACTTTTGATGCAACTGA TTTAGAGCGTTTGGCAACAA AGCTTCCACATCTGTAAATCCA TGGGCACACTGATTGGAGTA ACCGCTATCAGCTTCCTTTG CATATATGGCAATGGCAGCA TACGAGCGCCAAGTTCTTTT TGCCACACCATATTCTCCAA TTGCTCCCATATGCATCTCA TTGGTGATGGCGATGTAGAA GTTTCACTTCAGCCCAACCT ATTACGCGAACACCCAGAAC CATCATGACGAACGATTGCT AGATTTAATCAATGCAGTTGCAGA AATGCTTTACCAGCTTTGAATGCT GAATTCGAGACCGCTAGCGCTCGTTGGGTCGATGTCTATG GCGTATGGACCTAGGTATATCAATCTGTTCATAATGTAAGCGAATA ACCCCACAACCTAGGTATATAAAAGACCTCGTTACATTTATGGTG GATATCGGATCCGAGACCCTCGAAATTTATTCATTTTTCGATCC GAATTCGAGACCGCTAGCGCCCTGAAATGTGGAATAATGGCTA GCGTATGGACCTAGGTATATAGGGCGAAATGGGTTCTTAC ACCCCACAACCTAGGTATATTTAAGTATTTATTTCCTACAGTTAGGC GATATCGGATCCGAGACCCTTTTTGGTACTTCAACTTCATCCA GAATTCGAGACCGCTAGCGCACGGACCACTAGCTGACTCG GCGTATGGACCTAGGTATATTGTATAACCTTTGAACAACAATAATGA ACCCCACAACCTAGGTATATAAATGAATCCGATTTACGAGTGA GATATCGGATCCGAGACCCTCTTGTGGTTTTGCTTGCTGA GCGCTAGCGGTCTCGAAT AGGGTCTCGGATCCGATATC ATATACCTAGGTCCATACGCAGCTATGCAAT ATATACCTAGGTTGTGGGGTACAGCAATGAC GATAGAGTATAATTAAAATAAGCAGTTAACCATTACAAAAATTGTATAGAG TCAGATCTGTTAACGGTACCTGGGAATAAGAAATAAATAAAAACGA GATAGAGTATAATTAAAATAAGCTAACTAGATCACAGAGATGTGATGG TCAGATCTGTTAACGGTACCTATTTTAACGGCGGGTCTCA ATCGTTATACCAAATGACCGTTTATTAG GCGTAACACGTTGTCAGCTTCT ATCGCAACCGGATCATGGT AGCAGCAACTGAGTCTACAACTACAATA GCACGTGTTGCTGCGAAA CTTCAGGACTTTTACTAGAGCAATCG TGTTTGGAGCTGAACATGTCAAT TGTCGCCCATTTCTAATGCA TACGCGACGACACATCAAGC ACGATGCGCTAGAGGTTGCT GGGATGAATCTCCTGTAAACGTCA CGTTGATCGACTTCGGAACG CCAAGTTTCCGTCCTGGTGA GTTCCACGCCAACACCTGAT TGTGGCTTATGTAGGCATTGGTT CAAGCCACCTATGAATCCTTCG AGGCATTAATTTGACGGCAATG TTCGCGAAGTGTGTCTCGTTT GGCCGTTCAATCTCAAGTGGT TTGCATTGCCCCAAGTTGA CCAAGCACAAACACCGGGTA CCGCTATCGGTGGTGCTAAA TCCAAAATGTCGACCAGCAA CTGTAACACCCCCACGCATT TGCAGTTGATTGCATGACAGC CATTTAAACGTCGCGCACAA CGCCATCTTCAAATGGTCGT CCAATTTTCCCACCAACACG AGAGTAGCGACTGTATAATTTCTATTGAGG AAAGTGTACCCGAGTAGTCTTCCTTG AGGTTTTGGTTTCATCGAAAGAGA CGATGTCGAATTCAACTTTTTGG TTGTTCGTAACTTGCCGATTGA TTGGCGCATGTGGTAAATCA TTGCTGACGAAATCCAAGCA TGAACCATGTGAGCCAGGTG GCTGGCTACATGCGTCTAATTG TTGGCCTATTGCGTCAATCC TGGCATATTTGTCGGAGATCAA TCTGAAGCGTACCCTCTGTTTTG TGGATGAAAAAGGGGAACCA GTTGACCAGGGGCAACTTCA GTAGCTCAGAATGGGGCATCA TTGGTTGGCCTTGAGACTCC TGCGGTAGGTTCAGTATCAGCA GACCTTCGCCTGTCAAAATCC CAGGGGGAGCGATTAAACAA ATGAACCGAACGTCGCAAAC TTCCCCTGAAAAGAATAAGTTGTCA CCATCACATAGGCGCTTATCAA ATACGCCTGAGGAATTTTCTGGA TGCGAAAAGGATGCTTTCAAAT HG003 + pMAD*rsaA::tag47 1090169..1090037 19 19-26 71284..71607 212 227790..227666 11 21 -29 1133513..1133316 159 --168 212 -222 SAPhB194 + pRMC2RsaA 1242350..1242520 57 -67 228171..228581 151 2649263..2649064 85 187 -197 1085535..1085714 152 --159 144 -161 SAPhB162 + pRMC2RsaE 1490508..1490309 92 -105 2434732..2434509 1889320..1889190 17 10 -24 914081..914280 19 --25 93 --121 SAPhB163 + pRMC2RsaH 2237081..2236959 11 6 -17 1211921..1212120 1239594..1239472 89 47 -55 639887..639711 3 --8 108 --125 SAPhB302 + pRMC2RNAIII 2377463..2377315 6.25 21 -30 766854..767053 82 604871..605189 142 145 -153 630699..630979 127 --142 75 -96 AATCACATAACAAACATACCCCTTTGT 2612752..2612865 1 1 -8 1636654..1636455 116 1541730..1541535 20 18 -90 503065..502912 35 --42 111 -123 GTGTCTGAATACACGACGCTAAACA 2774384..2774078 296 -300 1795110..1794749 1113245..1113701 345 375 -409 250575..250690 43 --48 159 --212 CTTTGCTTGGAGTCCGTTCG 2775082..2774911 58.118 117 -127 1981577..1981718 28 993120..992921 85 57 -66 2781897..2781698 29 --48 27 -36 GCTGTCCCAGTTGCACCAAT 92424..92557 69 --84 2735193..2735055 1728492..1728293 157 84 -98 2413724..2413923 121 --133 87 --101 AAGCGAAGCGTTCGATGTTG 314008..313809 44.87 81 --95 667078..667277 1051518..1051810 108 110 -115 924110..924232 4 --31 90 --94 TTGCCCTCAGGACGTTGTTC 2323826..2324013 47 43 --53 1159617..1159834 102 174 -186 2567336..2567491 124 --130 GTTCCACCAAACAATCCAGCA 2128307..2128109 83 --110 1435623..1435424 65 65 -81 2623111..2622881 92 --136 GCCCCAACTTTACGCATCTG 492344..492419 40 --51 1754266..1754154 31 1 -15 2214138..2213937 85 25 -42 CGTTTCCTTTTGCAGAAACACC 1821370..1821473 75 --80 2162523..2162368 115 110 -122 2393726..2393558 52 55 -63 CAGGCAGCAATAACCCCATATT 1442876..1442703 41 35 --49 2338479..2338280 5 6 -14 429170..429315 33 26 -45 TTTATCTTGACGAGCGATTTCAGA 1274715..1274832 10 --24 854571..854372 84 75 --90 2641169..2641373 90 82 -97 GCACATGCAGAATTCAGAGCA 1248138..1248048 62 --66 2555347..2555491 29 26 -36 2677600..2677799 84 62 -84 TTGCTCTACTTGCAATCGCATC 1263356..1263518 47 --55 2349961..2349792 2 --13 1234835..1235034 187 88 -124 AGAGCGTCCTGTTGACGATGA 1123950..1123807 124 --131 2252348..2252232 3 1 -17 ?774234..774046 94 124 -136 TCCCCTGCTGAGATTTCTTCC 1088090..1087966 61 --70 2135568..2135369 36 --45 2136801..2136602 85 83 -97 TCCTTTAAGAAATGCGGGGTTA 904525..904724 88 87 --96 1826595..1826766 93 16 -27 2219308..2218767 201 7 -14 CTCATCACGACGGTGAACGA 896996..897195 166 --178 1627989..1627790 113 --127 201741..201970 123 36 -57 GGTGTTCCGGGTGAACAAGA 855514..855676 17 13 --22 1325761..1325523 125 128 -133 1599924..1600205 169 163 -176 CAATGTTGCCAATGGATCACC 714159..714358 88 82 --93 1026355..1026540 73 70 -78 2377581..2377709 16 13 -23 TTGCCAGAGAATTTGCCGTAA 682514..682642 16 10 --23 1013361..1013560 141 --148 1279179..1279378 49 27 -44 GCGTAACTTCGCTGATTGTTCC 569598..569470 8 --18 831415..831293 6 1 -15 145305..145504 96 117 -128 GCATGGAGCCCATTCATTGT 503130..503268 26 25 --31 466101..466300 75 --88 946642..946534 42 12 -22 190474..190629 53 --58
			215

Table 1 .

 1 Strains and plasmids used in this study

	S. aureus strain	Relevant genotype	Reference
	RN4220	rsbU tcaR	Ref 30
	NCTC8325 (RN1)	rsbU tcaR Φ11 Φ12 Φ13	Ref 24
	HG003	Φ11 Φ12 Φ13	Ref 26
	NCTC8325-4 (RN0450)	rsbU tcaR	Ref 24
	SH1000	tcaR	Ref 50
	COL	MRSA pT181	Ref 51
	SAPhB245	As RN4220 Δrnc	This study
	SAPhB701	As RN4220 Δrnc ECTO::rnc +	This study
	SAPhB809	As RN4220 Δrny	This study
	E. coli strain	Genotype	Reference
	DH5α	F-Φ80 lacZΔM15 Δ(lacZYA-argF) U169 recA1 endA1	Laboratory
		hsdR17 (rK-, mK+) phoA supE44 λ-thi-1 gyrA96 relA1	collection
	Plasmid	Property/use	Reference
	pMAD	Allele exchange	Ref 31
	pMAD2	Allele exchange with BsaI cloning	This study
	pMAD2-DErnc	rnc gene deletion	This study
	pMAD2-DErny	rny gene deletion	This study
	pECTO	S. aureus chromosomal ectopic complementation	This study
	pECTOrnc	rnc chromosomal ectopic complementation	This study
	pCN38	Expression in S. aureus	Ref 43
	pCN38-site1	pCN38 containing SAOUHSC_1580	This study
	pSAP-TA	pCN38 containing sapTA	This study
	pSAP-T*A	pSAP-TA derivative with the sapT gene inactivated	This study
		(replacement of its start codon by a stop codon)
	pCN38-site3	pCN38 containing SAOUHSC_2176	This study
	pCN38-site4	pCN38 containing SAOUHSC_2238	This study

Table 2 .

 2 Transformation frequency test. a The number represented the mean ratio with the RN4220 of three independent experiments * After 36 hours (instead of 16 hours). All clones are translucent.

		pCN38	pSite1	pSAP-TA	pSite3	pSite4
	Δrnc	1	0.5	< 0.003	0.4	0.5
				0.3*
	Δrnc ECTO::rnc +	1	1.2	0.9	0.2	1.2
	Δrny	1	1.3	0.9	0.2	1.1

a

Table 1 : Fitness experiments in different stress conditions

 1

	No Conditions sRNA mutants	20 o C 42 o C	pH 5.4	pH 8.68	NaCl 1.5M	H 2 0 2 0.1mM	RPMI	RPMI no folate	BHI no O 2	RPMI no O 2	BHI + DIP	BHI + serum 10% human	Blood Spleen Kidney Liver
		Sau60	
		Teg147				
		SsrS					
		Sau6528				
		RsaD					/
		RsaOV												
		Sau30		x						
		RsaH						
		Sau6836			/			x	
	10	Teg49									
	11 Sau6428	 
				 Under-represented in exponential phase
				 Under-represented in exponential-stationary-exponential phase
				 Over-represented in exponential phase
				 Over-represented in exponential-stationary-exponential phase
				x Disappearance

Scientific classificationDomain:

c Accession numbers: B. subtilis 168, NC_000964.3; E. coli MG1655; NC_000913.3.

Figure 16: Competition assay from liver samples in mouse model. Histograms representing the disappearance (lower bars) or accumulation (upper bars) of indicated deletion mutants (x-axis) in blood samples compared to an uninfected reference sample. Data are shown as average values and the standard deviation of ten samples in mix 1 is indicated.

Acknowledgments

This work has benefited from the facilities and expertise of the High-throughput Sequencing Platform of I2BC. We thank Thuong Van Du Tran for help with bio-computing analysis. We thank Sandy Gruss, Annick Jacq and George Killian for critical reading of the manuscript, helpful discussions and warm support.

Acknowledgements

We thank Tim Foster and Friedrich Götz for providing plasmids and strains. We thank Sandy Gruss, Annick Jacq and Hoega Arden for critical reading of the manuscript, helpful discussions and warm support. This work has benefited from the facilities and expertise of the high throughput sequencing platform of IMAGIF (www.imagif.cnrs.fr). This work was financed by grant ANR-2012-BLAN-1602-0120 (Duplex-Omics) from the Agence Nationale pour la Recherche.

Acknowledgments

We thank Marc Hallier (University of Rennes) for providing pCN38 and Ф80α, Libera Latino for technical advice on phage preparation and Claire Toffano-Nioche for help with bio-computing analysis. This work has benefited from the facilities and expertise of the High-throughput Sequencing Platform of I2BC. We thank Sandy Gruss, Annick Jacq and Mc Ewans for critical reading of the manuscript, helpful discussions and warm support.

brilliant comments and suggestion.

I grateful acknowledge the funding sourced for my thesis work. I was funded by the doctoral school scholarship (Gene Genome and Cell) for my first three years and was honored to receive the scholarship from Medical Research Foundation for fourth year. In addition, I was also supported by 3-month Vietnamese-France scholarship. In particular, I am grateful to Michel Jacquet for his continuous encouragement and his help for Vietnamese student.

Funding

This work was funded by Agence Nationale pour la Recherche (grant ANR-12-BSV6-0008 "ReadRNA"). TNLM was the recipient of a fellowship from the Foundation pour la Recherche Médicale (FRM).

Funding

This work was funded by Agence Nationale pour la Recherche (grant ANR-12-BSV6-0008 "ReadRNA"). TNLM was the recipient of a fellowship from the Foundation pour la Recherche Médicale (FRM).

Abstract

Bacterial gene expression is widely linked and controlled by growth conditions. Its tight regulation contributes to optimize bacterial fitness to environment. Many factors contribute to growth adaptions via transcriptional and post-transcriptional regulations and sigma factors, regulatory proteins and regulatory RNAs are key players. The identification of phenotypes associated with gene deletions is a classical method to find gene functions but may require testing many conditions for each studied mutant. Regulatory RNAs often contribute to fine-tune gene expression and phenotypes associated with their inactivation are often weak and difficult to detect. Nevertheless, minor phenotypes conferring modest advantages, may emerge as dominant traits after a few generations under selective pressure. Gene replacements with DNA barcode sequences allow monitoring many mutants simultaneously and detect weak phenotypes via fitness experiments. We adapted this strategy to deep sequencing and apply it to study regulatory RNAs in Staphylococcus aureus, a harmful animal, including human, pathogen. We constructed 39 Staphylococcal tagged-deletion mutants and tested their accumulation in competition experiments at different temperatures. Three and five tagged-deletion mutants were significantly underrepresented at 42°C and 20°C, respectively. One of the mutations, rsaOV, generated a strong growth defect at 20°C but not at 37°C or 42°C. Complementation and transcriptome studies indicate that rsaOV is within the cwrA 3'UTR and that the cold sensibility is directly associated to cwrA expression.

CHAPTER A2

Identification of sRNA phenotypes in S. aureus associated with growth adaptation and virulence

RESULTS

In addition to hot and cold temperatures, we tested the sRNA-deleted mutant set (in triplicate) previously described in competition assays with growth conditions mimicking situations associated with the infectious process. We also tested directly the fitness of mutants in a mouse model of infection. Experiments were performed as described in Chapter A2.

Adaptation to acidic and alkaline conditions

Acid and alkaline medium were obtained by adjusting the pH to 5.4 with 1M HCl or 8.68 with 1M NaOH, respectively. In acidic condition, no mutant had a significant phenotype in exponential phase (Sampling 1). Mutant sau30 seemed underrepresented but the standard deviation was too important for the observation to validate the conclusion (Figure 1). However, no read corresponding to mutant sau30 was detected when the mixed population went through stationary phase and underwent a second exponential growth phase (Sampling 2) at pH 5.4. The mutant sau30 completely disappeared under this growth condition (Figure 1). It is the most drastic phenotype that we observed among all tested conditions. The mutant sau6428 was also underrepresented in Sampling 2 (Figure 1).

The phenotype of mutant sau30 was confirmed by comparing sau30 and its parental strain growing individualy in a medium at pH 5.4 (Figure 2).

In alkaline growth medium, mutant sau6836 had a significant growth defect in competition assays (Figure 3) and its phenotype was exacerbated by growing the mix population to stationary phase and diluting it again (Figure 3). The phenotype was confirmed by growing sau6836 and its parental strain separately in an alkaline medium (Figure 4).

CHAPTER B

Author summary

Bacterial small RNAs (sRNAs) are key regulators of homeostasis and adaptation responses that usually base-pair with their target RNAs. To decipher sRNAdependent networks of Staphylococcus aureus, we developed a method to trap sRNA targets that combines RNA-seq, differential computational analysis and an in vivo validation step. We applied this strategy to investigate the function of four staphylococcal sRNAs; numerous targets were validated and specific roles for these sRNAs were assigned. One of them, RNAIII, is a paradigm for complex bacterial sRNAs and a virulence factor regulator that has been studied for over two decades. Here, we identified new RNAIII targets revealing that expression of virulence factors and iron import functions are coordinately controlled by a single sRNA.

IntaRNA V.1.2.5 package [13] and consensus motifs in putative target sequences using the MEME suite V.4.9.0 [41]. We searched for the motif with highest raw counts using different combinations of MEME parameters as described in Supporting Information. The standard SD motif (Fig S2) was identified by MEME using as input the 1114 S. aureus sequences for which a TSS could be identified by the above protocol.

Quantitative reverse transcriptase PCR and northern blots. qRT-PCR experiments were performed on a subset of putative targets selected among the most enriched mRNAs of each Hybrid-trap-seq set (see Supporting Information for details). Experiments were performed on biological triplicates and data were analyzed as described [42]. Northern blots were performed as described [43].

Abstract

RNase III is a conserved double-strand-specific endoribonuclease. In bacteria, it contributes to i) bulk RNA degradation, ii) reducing pervasive transcription and iii) maturing both rRNAs and mRNAs. In Bacillus subtilis, RNase III is essential, and ensures protection against Type I toxin-antitoxin (TA) systems by degrading antitoxin RNA-mRNA duplexes. Despite its involvement in essential functions, RNase III is dispensable in several bacterial species, presumably due to functional redundancy with other ribonucleases. Deletions in rnc (encoding RNase III) were previously constructed in Staphylococcus aureus and therefore RNase III was reported as non-essential in this human and animal opportunistic pathogen. Surprisingly, the rnc gene could not be deleted in HG003 S. aureus strain, which contains three prophages that are absent in strains in which rnc was dispensable. Phage-encoded RNA duplexes were thus candidate RNase III targets. A cloned Type I TA system, named here SapTA, encoded by one of the HG003 prophages, had no effect on the wild type strain, but was deleterious in the absence of RNase III due to the expression of the SapT toxin. Two phages produced clearer plaques when spotted on a rnc strain than on its corresponding wild type isogenic strain. These results show that RNase III provides a selective advantage in the presence of phages. With this method, we are able to detect mutants leading to advantageous or disadvantageous growth phenotypes. In addition, some mutants having moderate phenotypes can be characterized. Phenotypes associated with sRNA-deletion found via fitness experiment can sometime be confirmed by compairing mutant and parental strains growing individually in the tested conditions. However, some phenotypes cannot be observed by simple growth curves. The fitness test allows the identification of subtle differences cumulating over the experience. In addition, some phenotypes may depend on the presence of other strains.

Supplementary data

Deciphering RNase III essentiality in Staphylococcus aureus

Thirteen growth conditions (12 stresses and mouse model) were tested and analyzed. We obtained 11 strains having significant altered fitness in at least one of the tested conditions. Among them, mutants sau60, teg147, ssrS have an effect in only one condition (Table 1, Figure 18).

MgrA is a direct activator and NorG is a direct repressor [START_REF] Truong-Bolduc | The Transcriptional Regulators NorG and MgrA Modulate Resistance to Both Quinolones and ??-Lactams in Staphylococcus Aureus[END_REF]. Moreover, Rot, SarA, and SarZ are also direct regulators of abcA [START_REF] Villet | Regulation of Expression of abcA and Its Response to Environmental Conditions[END_REF]) (Figure 19). No change of abcA and pbpD expressions under acidic pH, oxidative stress (H 2 O 2 ), iron limitation was observed while the transcripts of abcA increased only under nutrient limitation condition [START_REF] Villet | Regulation of Expression of abcA and Its Response to Environmental Conditions[END_REF]. Therefore, Sau6836 is likely the 5'UTR of SAOUHSC_00647 an may affect pbpD and abcA expression. However, this system is complex and the role of Sau6836 toward growth in alkaline condition remains to be explained. *, NorG is absent from MW2. Effector indicates a direct regulator that can be a repressor or an activator depending on the strain and the environment [From [START_REF] Villet | Regulation of Expression of abcA and Its Response to Environmental Conditions[END_REF]].

Adaptation to high osmolarity and oxidative conditions

Mutant teg147, sau6528 and rsaD were underrepresented in high osmolarity condition. Mutant rsaD is described in Chapter A1. Teg147 is a bona-fide sRNA BIBLIOGRAPHY