Mouaad Hafsi
email: hafsi.mouaad@gmail.com

Saïd Assar
email: said.assar@imt-bs.eu

Proposal of a visual impact analysis approach based on enterprise modeling: Case of customer experience projects in the banking sector

Keywords: Digital transformation, Customer experience, Enterprise Architecture, Enterprise modeling, Impact analysis

Customer experience is often presented as a competitive battlefield; however, it is defined so broadly, so holistically that companies find it challenging to implement and to analyze its impact on increasingly complex information systems. In this perspective, we present a support approach for digital transformation projects around the customer experience, using a visual impact analysis based on enterprise modeling. We illustrate the use of this model in a real banking environment.

Introduction

With the emergence of new digital technologies, the banking world is not spared by the arrival of new players, in particular bionic banks (100% digital), which are shaking up value chains and putting traditional players in a position to react vigorously to face this new competition [START_REF] Forrester | Banking of the Future: How Banks will use digital capabilities to remain competitive[END_REF]. The banking industry has therefore embarked on gigantic, multiyear strategic digital transformation programs. Thus, the banking sector is at the forefront [START_REF] Sorofman | Gartner Surveys Confirm Customer Experience Is the New Battlefield[END_REF] and ranks 4th among the most digitally transformed sectors. A panoramic reading of the latest strategic plans announced by all most banks indicates an acceleration of the pace with colossal spending forecasts. For example, the BPCE banking group in France calls its strategic plan TEC2020, whose name highlights the importance of technologies in its transformation [START_REF] Bpce | Le plan stratégique 2021-2024 du Groupe BPCE[END_REF] with an investment forecast of 750 million euros. One of the main reasons for these investments is the potential capacity of new technologies to improve the customer experience [START_REF] Duan | Evaluating the critical determinants for adopting e-market in Australian small-and-medium sized enterprises[END_REF][START_REF] Westerman | The nine elements of digital transformation[END_REF][START_REF] Piccinini | Changes in the Producer-Consumer Relationship -Towards Digital Transformation[END_REF]. This customer experience is, more and more, considered as the new competitive field of marketing. In one of its publications, the Consulting Firm "Gartner" underlined that 57% of customers stopped buying from a company because a competitor offered a better experience [START_REF] Sorofman | Gartner Surveys Confirm Customer Experience Is the New Battlefield[END_REF]. According to an empirical survey of the same study, it also found that 67% of customers say they are willing to pay more for a better customer experience. Customers are accustomed to digital interaction in many areas of daily life; likewise, they demand financial services that are available 24/7 and as user-friendly as the social networks they use every day [START_REF] Piccinini | Changes in the Producer-Consumer Relationship -Towards Digital Transformation[END_REF][START_REF] Nava | The Millennials Paradox. U.S. Banking watch[END_REF][START_REF] Sahu | Investigating The Critical Success Factors Of Digital Transformation For Improving Customer Experience[END_REF].

This change in consumer habits forces banks to tackle their customer process as a matter of urgency so as not to be left behind in a rapidly changing market. However, the undertaken projects often remain at the starting point [START_REF] Forrester | Banking of the Future: How Banks will use digital capabilities to remain competitive[END_REF]. This is, for a large part, due to the complexity of the implementation of this transformation; indeed, it is a complex process [START_REF] Berman | Digital transformation: opportunities to create new business models[END_REF][START_REF] Nwankpa | IT Capability and Digital Transformation: A Firm Performance Perspective[END_REF], affecting several areas and components of the organization. It involves managing the volatile behavior of customers, understanding their complex data [START_REF] Nwankpa | IT Capability and Digital Transformation: A Firm Performance Perspective[END_REF], carrying out numerous optimizations of customer processes [START_REF] Berman | Digital transformation: opportunities to create new business models[END_REF] and transforming business models organization [START_REF] Nwankpa | IT Capability and Digital Transformation: A Firm Performance Perspective[END_REF] to integrate various digital technologies [START_REF] Bharadwaj | Digital Business Strategy: Toward a Next Generation of Insights[END_REF] and to adapt to changing business conditions [START_REF] Matt | Digital Transformation Strategies[END_REF].

This implementation is more complex as organizations do not have the "privilege" of starting from a blank sheet to design their customer experiences. Most have already established customers, processes and assets that require reorientation to achieve specific customer experience strategies. Based on our expertise in digital transformation consulting, we observe that managers suffer from the lack of tools allowing the analysis of the existing to define a coherent target strategy. Consultants often tend to launch their projects from scratch and design ideal transformative customer experiences almost independent of the business's actual context. With this in mind, this article proposes a visual analysis approach allowing managers to lead the transformation better by analyzing their impacts on the company and considering the existing environment. As an example of transformation, we examine projects around improving the customer experience.

This approach is based on the Enterprise Architecture (EA) to define an Information System target strategy (To-Be) and a planning of activities and resources based on the existing business environment (As-is) [START_REF] Lange | An empirical analysis of the factors and measures of Enterprise Architecture Management success[END_REF][START_REF] Rouhani | A systematic literature review on Enterprise Architecture Implementation Methodologies[END_REF]. This article relies on a new Enterprise Model [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF] used as part of a real banking transformation around the customer experience. This study aims to help managers better understand the contribution of EA and EM in supporting digital transformation.

The paper is organized as follows. Section 2 presents a literature review. Section 3 retraces the scientific basis of the model that we use in our case study [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF], section 4 presents the case study and the results obtained. Section 5 concludes the paper.

2

Context and background

2.1

The customer experience, a major shape of the digital transformation Digital Transformation (DT) operates a radical change in the structure, processes, functions and business models of an organization [START_REF] Matt | Digital Transformation Strategies[END_REF][START_REF] Westerman | Leading digital: turning technology into business transformation[END_REF], this change is driven by the adoption of digital technologies for the purpose of improving company performance [8,17. Digital transformation promises organizations many benefits, including improved organizational processes [START_REF] Matt | Digital Transformation Strategies[END_REF][START_REF] Fayon | Measuring the digital maturity of players in the banking sector in a digital transformation perspective[END_REF][START_REF] Hafsi | Does enterprise architecture support digital transformation endeavors? Questioning the old concepts in light of new findings[END_REF], improved customer value propositions [START_REF] Duan | Evaluating the critical determinants for adopting e-market in Australian small-and-medium sized enterprises[END_REF][START_REF] Fitzgerald | Embracing digital technology: A new strategic imperative[END_REF], improved service quality [START_REF] Rajabi | Business Transformations: Inevitable Changes of the Era[END_REF], cost reduction [START_REF] Duan | Evaluating the critical determinants for adopting e-market in Australian small-and-medium sized enterprises[END_REF], innovation and improved customer experience [START_REF] Fitzgerald | Embracing digital technology: A new strategic imperative[END_REF] and increased revenue [START_REF] Westerman | Leading digital: turning technology into business transformation[END_REF].

The study by [START_REF] Westerman | Revamping Your Business through Digital Transformation[END_REF] summarizes the facets of DT in three main areas: a) Customer experience; b) Business processes; c) Business model. Each of these three areas is divided into three sub-elements. The customer experience is broken down into three sub-elements: customer understanding, revenue growth, and customer touch points. What is interesting is that traditionally the customer experience has only been viewed from the perspective of different touchpoints [START_REF] Rawson | The truth about customer experience[END_REF]. Westerman et al. paint a more complete picture by adding elements around streamlining sales and digital marketing processes, as well as new capabilities to better understand customers and their volatile behaviors [START_REF] Westerman | Revamping Your Business through Digital Transformation[END_REF]. Numerous studies have examined the implementation of digital transformation to improve the customer experience. [START_REF] Matt | Digital Transformation Strategies[END_REF], for example, assess strategies and target policies around the customer experience [START_REF] Matt | Digital Transformation Strategies[END_REF]. [START_REF] Klaus | Exploring the role of the online customer experience in firms' multichannel strategy: an empirical analysis of the retail banking services sector[END_REF] and [START_REF] Kane | Strategy, not technology, drives digital transformation[END_REF] examine engagement processes to improve the customer experience [START_REF] Klaus | Exploring the role of the online customer experience in firms' multichannel strategy: an empirical analysis of the retail banking services sector[END_REF][START_REF] Kane | Strategy, not technology, drives digital transformation[END_REF]. [START_REF] Berman | Digital transformation: opportunities to create new business models[END_REF] and Westerman (2014) analyze critical factors to reshape the customer value proposition [START_REF] Berman | Digital transformation: opportunities to create new business models[END_REF][START_REF] Westerman | The nine elements of digital transformation[END_REF]. These studies tend to focus mainly on defining the customer experience and its ecosystem in the company. Few attempts have been made to develop a comprehensive approach to helping managers deploy these projects by analyzing their impacts on the business and by considering its existing environment.

Enterprise architecture and its contributions

There are different definitions of Enterprise Architecture (EA). They can generally be classified into two different categories [START_REF] Hoogervorst | Enterprise architecture: Enabling integration, agility and change[END_REF]: descriptive and prescriptive. Descriptive definitions generally consider architecture as a set of models that document how the business is built and how it operates. Op't Land et al. (2008) define it as: "A coherent set of descriptions, covering a perspective oriented towards a shared target, the EA provides indicators and controls which allow an informed governance of the evolution and the business success" [START_REF] Op't Land | Enterprise architecture: creating value by informed governance[END_REF]. The prescriptive, normative school in turn focuses on the construction process and the rationale for a business transformation. An example of this category is the definition of the Federation of Professional Organizations of Enterprise Architecture (2013): "A well-defined practice to perform the analysis, design, planning and implementation of actions of the business, using a holistic approach to the successful development and execution of strategy" [START_REF]The Open Group: ArchiMate® 2.1 Specification[END_REF]. Over the years, studies have linked several benefits of EA. These are generally indirect, large-scale, company-wide, and perceived over a long period of time, which makes it difficult to calculate an exact return on EA investment [START_REF] Rico | A framework for measuring ROI of enterprise architecture[END_REF]. However, in the very rare cases where the ROI has been calculated, the results appear remarkable [START_REF] Rico | Optimizing the ROI of enterprise architecture using real options[END_REF].

How to position EA in the business ecosystem, how could it work in practice as part of improving the customer experience?

The relationship between EA and business strategy has already been explored in the literature. The best-known example of this school of thought is the concept of the "execution foundation" proposed by [START_REF] Ross | Enterprise architecture as strategy: Creating a foundation for business execution[END_REF] [START_REF] Ross | Enterprise architecture as strategy: Creating a foundation for business execution[END_REF]. They explain how an organization can better execute its strategy and facilitate continuous change with the help of EA. For [START_REF] Ross | Enterprise architecture as strategy: Creating a foundation for business execution[END_REF], each company has its own execution foundation; this foundation sets certain limits on future business strategies. To perform these continuous changes, certain capabilities are required, such as IT infrastructure and business processes. The EA model, which is derived from the organization's operational model, defines these basic capabilities and provides documentation to understand them and understand their dependencies. The EA also provides the best practices for implementing changes that are inevitable when executing strategic initiatives. To build an adequate foundation for conducting business strategies, companies must, according to the study, master three key elements (Fig. 1):

Operating model. The operating model describes the necessary level of integration and standardization of customer processes to master the customer experience. Companies have different levels of process integration in their business units. The integration enables end-to-end processing and a single face for the customer; it forces a common understanding of data across various business units.

Enterprise architecture. EA represents the organizational logic of IT in the service of business processes. It covers the integration and standardization requirements of the company's operating model. EA models offer rules, standards to be respected, and a long-term view of a company's processes, systems and technologies so that projects can develop sustainable capabilities, and not just meet immediate needs.

The engagement model. Also known as the enterprise model, represents the governance mechanisms that ensure that business and IT projects achieve desired objectives. The engagement model influences project decisions so that all solutions are guided by the rules and standards enacted by the company's architecture. The engagement model aligns the IT and business objectives of the projects and coordinates IT and business decisions taken at several levels. We will attempt in our case study this contribution using the enterprise model of [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF]. In the context of digital transformation and rapidly changing industries (e.g., banks), an interesting angle around strategic initiatives deserves to be taken up: the concept of emerging strategies versus deliberate strategies [START_REF] Mintzberg | The strategy process: concepts, contexts, cases[END_REF]. The emergence of new technologies (e.g., Artificial Intelligence, Data Analytics, etc.) shapes the strategies formulated previously and how companies could have implemented them. The execution foundation enriched with new technologies no longer serves to set certain limits to future business strategies. It must henceforth help define new emerging strategies necessary for the company's survival in today's digital context.

In the next section, we will use an enterprise model to help managers perform visual impact analysis as part of a banking transformation with the goal of improving the customer experience.

Use of the digital transformation-oriented enterprise (DTO) model

We use the enterprise model from [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF] for our case study. We rely on this because it allows a simple visualization (not very technical) accessible to managers. This model was built respecting the design science protocol described by [START_REF] Hevner | Design Science in Information Systems Research[END_REF]. It uses the concepts of ArchiMate [START_REF]The Open Group: ArchiMate® 2.1 Specification[END_REF]; we will only use some of these concepts for our case study. The next chapter reviews the structure of this model and its architectural foundations.

DTO Principles: Flexibility by Design

In today's banking world, the economic success of a bank depends on its ability to react to change quickly and flexibly. According to [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF], the flexibility and agility of organizations are identified as necessary conditions to facilitate the digital transformation of organizations [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF]. This flexibility is based on the degrees of autonomy available in the organization. It is an internal response to the speed of external change The concept of "decoupling" highlights the structural constraints inherent in the company and presents them as one of the key elements of the organization. Therefore, according to [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF], improving flexibility means: "Seek to reduce the coupling between certain entities of the organization". Faced with this search for flexibility, the objective is to identify the decoupling levels; two levels are identified (Figure 2).

Vertical decoupling.

Regarding the best practices supported by the Open Group (2017), [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF] recommends the separation between the process layer and the organizational environment layer [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF]. Indeed, to manage the company transformation, process changes must potentially be decoupled from changes in the organizational context. For example, a change of human resources, in the structuring of the databases, or even in the application solutions, can be introduced without impact on the concerned process. The same process must be simulated in several alternative environments; for example, the same process can be implemented in several production sites. Its simulation within these different sites will allow it to assess its performance according to the environment or facilitate its transfer between two sites.

Therefore, [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF] distinguish between a "process" view and an "organizational environment" view:

-The "process" layer describes the entire business process at different levels of granularity. This layer is made up of different types of processes: informative and physical.

-The "organizational environment" layer groups together objects which operate on the company's environment and which may have an impact or be impacted by its behavior.

Using this model for our case study would allow us to qualify the degree of decoupling of processes from their organizational environment.

Fig. 2. The DTO model canvas (Hafsi et al., 2018) [15]

Horizontal decoupling. This decoupling is part of a goal to separate the processes by their nature and according to the objectives achieved by these processes. This horizontal decoupling is presented in two distinct views of modeling.

-View of production processes includes all the services and data necessary to support and manage the products owned by customers. It is "the factory of the company". Its objects also include all production services of a transversal nature: Archiving, Editing, Manufacturing, Invoicing, Taxation ...

-View of distribution processes: customer-oriented, this view includes all the business capabilities and customer processes necessary to develop the business and manage the customer relationship (pre-sales, sales, and post-sales).

In the context of digital transformation, this distinction between these two layers is more necessary as the response to customer needs must be transparent and isolated from the concerns of production processes and internal support [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF]. Using this model for our case study would qualify the degree of decoupling between distribution and production processes.

Modeling external factors.

In the context of digital transformation, companies are exposed to their environments, it is necessary to control external factors such as social and regulatory constraints. Other factors such as key trends, market forces, industry forces and macroeconomic forces should be identified [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF]; these elements seem to have an impact on all parts of the business and cannot be dealt with in isolation from the others.

Case Study

Industrial context

For confidentiality reasons, we call the company where we operate "ITBank X". "ITBank X" is an internal services company of a large European banking group. Its 1,600 employees develop and maintain the information system of member banks. "ITBank X" also contributes to developing the IS roadmap, which is a multi-year business plan focused on users and customers. This roadmap is fed into the business projects undertaken each month by the bank representatives who represent their peers on the IS Decision-making Committees. ITBank X has launched a major digital transformation program we call "DIGI TRANSFO", it shows a real desire to transform in the service of its customers.

Expected objectives

Two categories of objectives are pursued in this study:

-Scientific: Explore the contribution of Enterprise Architecture in supporting digital transformation projects using enterprise modeling. This use is a continuation of research work around the DTO model [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF] and is part of the process of evaluating the model in a real industrial field [START_REF] Hevner | Design Science in Information Systems Research[END_REF].

-Industrial: Help ITBank X map its existing processes and applications related to the customer experience, then use this mapping to analyze and visualize the impact of new projects initiated on the business environment. For this paper, and for confidentiality reasons, we are limiting ourselves to certain customer experience processes and we are exposing a reduced scope for illustration.

Mode of intervention

The two objectives were clearly identified from the start of the intervention, and the mission sponsor is aware of our dual role: consultant and researcher. Our intervention lasted 6 weeks full time to carry out the analysis methodology described in [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF].

Analysis methodology

Step 1 -Instantiation of the DTO model: In this first step, the company discovers the model, we decide with the sponsor the level of detail expected by our analysis, the scope of our intervention and the stakeholders who will participate in the study, the choice made is as follows:

-Granularity of the objects visualized on the model: Macro process, application, integration application, external factors (banking regulations and technological trends), we use the concepts of ArchiMate 3.0 taken up by the DTO model.

-Scope: this is the functional perimeter dealing with the entire customer journey, from his contact with the company to bank charges, it is an end-to-end vision covering the customer journey but also the induced of this journey in the company's support processes.

-Participants: As part of this study, we are working with business experts in the field of banking distribution and processes already documented and implemented, with application managers in the distribution scope, and then with architects with a strategic, business, and IT transverse vision.

Step 2 -Mapping the processes on the DTO model: In this step, we work with the business experts to map the macro distribution process covering the customer journey and impacting the customer experience and the production processes necessary to achieve them. We have identified 8 macro processes (figure 3).

Step 3 -Mapping the applications on the DTO model: In this step, we work with the application managers to map the applications covering all the processes mapped by the business experts. We then identified the integration capabilities that these applications need for them to function properly. We identified 10 applications and 2 integration applications (Figure 3).

Step 4 -Inventory of external factors: We asked all the participants, based on the framework of the DTO model [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF], what were the external factors that could impact the functioning of the current ecosystem, we identified two categories: banking regulations and technological trends (Figure 3).

Step 5 -Analyze the existing architecture principles: Based on the DTO model (Figure 4) and its architectural principles, we analyze the concepts of flexibility and decoupling by answering these questions:

-Do the process and the application respect the right granularity? The process and the application must meet one and only one business objective.

-Are the process and application of distribution well decoupled from those of production?

Step 6 -Analyze the gaps between customer experience processes and existing applications: Based on the DTO model and its architectural principles, we analyze the alignment of IT on the business (figure 4) by answering these questions:

-Are all the processes covered by the applications? -Does the application meet a business purpose? Step 7 -Visualize the alignment of IT on customer experience processes: For a given business objective, visualize the process and all the applications and integration application that carries it, this will give better visibility for the manager of the ecosystem for achieving this business objective (figure 5).

Analysis results

We follow the method proposed by [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF] to analyze the results of using the model and its instantiation [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF].

Knowledge sharing through simple visualization.

The managers confirmed that the instantiated model (Figure 3) provided an easy-to-understand visualization of the scope covering the customer experience (process and application). The objective of sharing common knowledge has been achieved. This shared vision allowed participants to propose new ideas (eg. having customer knowledge management from social networks) which were not part of the business objectives expressed previously.

Analysis the DTO model architecture rules. Mapping analysis of DTO model allowed us to ask questions about the scalability of the company's components, we observed 3 types of non-compliance with architecture rules (figure 4):

-Non-decoupled application: the application numbered 7 performs both distribution and production processes.

-Non-rationalized applications: Applications 11 and 12 all meet the same business objective (cost accounting), this often generates, according to application managers, a redundancy of the results obtained, more surprisingly, these produced results are sometimes not the same because applications 11 and 12 have different management rules, developed differently by different teams.

-Process meeting several business objectives (e.g., Marketing and support). This induces very expensive transformations because they are not delimited and well framed (not targeted by process), This analysis allowed managers to be aware of the need to be more flexible in an environment such as that of the bank, which is constantly changing. The managers would like to examine proposals for new information system transformation projects (applications and processes) to acquire sustainable development capacities for the next digital transformations [START_REF] Ross | Enterprise architecture as strategy: Creating a foundation for business execution[END_REF].

Identification of new needs to improve the customer experience and impact analysis through visualization of the alignment. During our mapping work, the business experts identified a new need that could improve the customer experience It is based on a new technological trend known in the banking world as "Logics and eventoriented architectures or asynchronous mode". The business experts have expressed their desire to take advantage of this technology to cover a business need: Cross-Channel accessibility; it is the possibility of a customer switching from one distribution channel to another, using a real-time notification system, without interrupting the journey. Thus, the customer could start his credit application at a branch and finalize it on his smartphone or another available channel. This is an example of a business need identified from a technological capacity in the market. The analysis of this new need using the model (figure 5) allowed managers to place it in the company's ecosystem. This facilitated the ability to detect: a) Existing processes and applications including business needs to deploy this new need; b) New applications or processes to be defined and implemented; c) Integration applications to be defined and implemented (e.g., the ability to manage events and their integration into the ecosystem).

Reflection on the use of the model

Through the application of the DTO model, we gathered feedback regarding the its applicability and usefulness. According to the participants, the analysis based on the DTO model was helpful and met their expectations. The model focused on IS agility issues and allowed "unspoken needs" to appear in an easy to understand way:

-According to managers, using the DTO model enabled them to carry out impact analysis to support their transformation projects, based on a visualization of the existing environment. This visualization made it possible to share knowledge and raise awareness of the sustainable capacities for evolution (organizational agility) that the bank should develop to be able to keep up with the accelerated pace of digital transformations.

-According to managers, the analysis was relevant. In addition, most of them felt capable of reusing the DTO model on their own for their next IS diagnostic needs upstream of transformation projects.

-According to managers, the study was successful in terms of results and findings, as it confirmed and reinforced some of their own perceptions on the agility and the structuring needs of the IS. This allowed them, for example, to focus more on certain integration bricks belonging to the generic layer of the model.

-The participants unanimously validated the relevance of the concepts and requirements of the DTO model (decoupling, modularity, modeling of external factors, etc.).

-Some participants gave us some recommendations on the instantiation process and how to involve participants. For example, it was requested to merge the 3 phases of Mapping in the same meeting to allow business experts, application managers, and architects to discuss more business issues. This would push the brainstorming mind into thinking to imagine other ways of optimizing the IS.

-Finally, an architect (ArchiMate Certified) preferred a more complete architectural model with full instantiation of all ArchiMate concepts. For him, it would be better to be able to identify all the design problems of an IS component.

Conclusion

According to the literature and our experience in digital transformation consulting, improving the customer experience is a complex process. For this, we used the DTO model of [START_REF] Hafsi | Towards a Visual Modeling Approach to Manage the Impact of Digital Transformation on Information Systems[END_REF] to help managers carry out their impact analyzes of this complex process using a visualization of the existing environment. This visualization allowed managers to share knowledge and raise awareness of the sustainable capacities for evolution (flexibility by design) that the bank should develop to be able to keep up with the accelerated pace of digital transformations.

Fig. 1 .

 1 Fig. 1. The foundation for the execution of (Ross et al., 2006)

Fig. 3 .Fig. 4 .Fig. 5 .

 345 Fig. 3. Mapping of processes and applications


Stéphanie Coantic--Castex

Agathe Martinez

Dominique Harakat

Dominique Guillaume

Pascale Clivio

The Remarkable UV Light Invulnerability of Thymine GNA Dinucleotides

We herein demonstrate the UV resistance of glycol nucleic acid (GNA) dinucleotides. This resistance sustains the hypothesis of GNA as nucleic acid prebiotic ancestor on early Earth, a time of intense solar UV light. Such photorobustness, due to absence of intrastrand base stacking, could offer opportunity for nanodevices development requiring challenging UV conditions.

Glycol nucleic acid (GNA) is a nucleic acid analogue that exhibits the structurally simplest and minimal phosphate backbone capable of high duplex stability. 1,2 The GNA backbone is made of a succession of α--propylene glycol phosphodiester units affording (S) or (R)--GNA enantiomers (Fig. 1). The facile chemical access to these polymers combined to their remarkable hybridization properties offer unprecedented perspectives in structural and functional nucleic acid--based nanotechnology.

3

In the medicine field, GNA has also been used to probe the folding topology of G quadruplexes and to improve the therapeutic index of siRNA.

4,5 Fig. 1 Structures of DNA, RNA and (S)-- and (R)--enantiomers of GNA.

Finally, the accommodation of some polymerases with the glycol motif makes this artificial polymer highly attractive for the evolution of functional GNA by in vitro selection. 6 The structural resemblance of GNA and nucleic acid, and the possible genetic information transfer between these two species have led to propose GNA as a predecessor of contemporary nucleic acids.

1,6a,7

In early earth when life formed, surface UV radiation level was much higher than at present.

Consequently, nucleic acids had to face these harsh UV conditions to avoid deleterious consequences for the cell. Meanwhile, the UV vulnerability of nucleic acids is considered to have played a key role in shaping the adaptation and evolution of life through PP induced mutations. 10 Therefore, suggestion of GNA as a nucleic acid ancestor rises the crucial question of its UV photoreactivity. To address this question, we studied the photochemical behaviour of GNA dinucleotides when exposed to far UV light. Considering that 1) UV--induced DNA damage arises mostly between adjacent pyrimidine residues, dithymine sites being the most reactive ones, and results in three types of dipyrimidine PPs: cyclobutane pyrimidine dimers (CPDs), (6--4) and Dewar 112) UV--induced pyrimidine hydrate formation in DNA is a minor process with respect to dipyrimidine PPs formation, 12 and that 3) thymidilyl--(3',5')--thymidine (TpT, 1) is sufficient to mimic the photoreactivity of the same sequence in DNA, 13 we synthesized GNA analogues of 1 and studied their photochemical behaviour, anticipating 1 to be a good model compound to study the photochemistry of GNA. Due to the easiness of the synthetic protocol, we synthesized all four diastereomers, the two homochiral enantiomers (S,S)--GNA TT 2 and (R,R)--GNA TT 3, as well as the heterochiral enantiomers (S,R)--GNA TT 4 and (R,S)--GNA TT 5 (Fig. 2) in view of future experiments. Therefore, this study gave us the opportunity to synthesize for the first time heterochiral GNAs then to The synthesis of 2--5 made use of the known tritylated thymine glycol nucleosides (R)--6 and (S)--6 1 (Scheme 1). For example, to prepare 2, a one step acetylation detritylation procedure of (S)--6 afforded (S)--7 in 83% yield. Phosphoramidite (S)--8, 1 synthesized from (S)--6 was condensed to primary alcohol (S)--7 in acetonitrile in the presence of imidazolium triflate and the resulting phosphite triester was oxidized with t-butylhydroperoxide. Concentrated ammonia followed by aqueous acetic acid treatment of the phosphate triester afforded 2 that was purified by RP HPLC and isolated in 2% yield (four steps). Scheme 1. Synthesis of GNA TTs. Shown is the route leading to (S,S)--GNA TT 2. Reaction conditions: (i) Ac 2 O, pyridine; (ii) TFA, CH 2 Cl 2 ; (iii) Imidazolium triflate, CH 3 CN; (iv) t--BuOOH in nonane; (v) conc. NH 4 OH; (vi) 80% aqueous AcOH. Aqueous solutions (2 mM) of (S,S)--GNA TT 2, (R,S)--GNA TT 5 and TpT 1 as a standard were individually exposed to 254 nm radiation. UV monitoring of irradiation reactions of 2 and 5 revealed no significant change in UV absorbance around 270 nm and 330 nm after 3 h indicating that the thymine chromophore remained intact. In contrast, a loss of ~ 50% in 270 nm absorbance of 1 attested that approximatively half of the thymine residues had reacted (Fig. S25, ESI †), in addition, appearance of an absorption near 330 nm attested of the formation of the (6--4) PP In addition, only favourable base--stacked geometries will induce photoproducts formation. 17 Therefore, we investigated the stacking properties of homochiral (S,S)--2 and of heterochiral (R,S)--5 by circular dichroism (CD) to establish its possible involvement in the photostability of GNA dinucleotides 2 and 5 (Figure 3). The CD spectra of enantiomeric (S)-- and (R)--thymine GNA 9 as well as those of 3 and 4 were recorded for comparison. Fig. 3 CD spectra of 2--5 and 9 at 10°C. The CD spectrum of TpT (1) at 10°C is shown for reference. The negative long--wavelength CD band of homodimer (S,S)--2 is consistent with an (S)--GNA oligonucleotide structure. 1,2b,6a The limited CD amplitude difference between 2 and its constituent monomer (S)--9 indicated that the CD signal of 2 is roughly the exclusive result of the chiral centers of its glycol phosphate backbone. (R,S) Dimer 5 displayed a small positive CD signal around 270 nm (Fig. 3) whose significancy was nevertheless attested by the mirror image CD spectrum of the (S,R) enantiomer 4. In the absence of base interaction, no CD signals should be expected for heterochiral diGNAs. Therefore, the CD signals of 4 and 5, even low, attested of a weak but detectable interbase interaction. The shifts of the maximal CD bands of 2 and 5 with respect to 1 (λ ∼ 280 nm for 1 versus λ ∼ 272 nm for 2 or ∼ 268 for 5) indicated that the geometry pattern of this interaction in 2 and 5 is different from that of TpT (1) (Fig. 3). Hence, the small CD signal of 2 and 5 could be due to either a very low population of CD responsive stacked species or a population of stacked species devoid of intense CD signal, 18 two hypotheses that, at this stage were impossible to dissociate. Consequently, we performed the conformational analysis of 2 and 5 in solution by NMR (see SI for details).

In the solid state and in simulated solution, the major conformational characteristic of homo GNA duplexes is an almost complete absence of intrastrand base--base overlapping which is the predominant mode of base interaction in DNA. Please do not adjust margins

Please do adjust margins

In solution, homo single strand (ss) GNA is preorganized in a conformation similar to that of the individual strands of homo GNA duplexes. 2b Therefore, conservation of the large sliding between adjacent bases in ssGNA can be hypothesized. This unusual interbase stacking mode, if present in homo diGNA 2, could explain its UV hardiness in solution. Single GNA nucleosides in solution 2b and some GNA nucleoside residues within GNA duplexes in the solid state 19,20 and in simulated solution 20 adopt the same conformation ( η, ζ and γ (Fig. 1) in the g--domain). Our study indicated that, in solution, both GNA nucleoside units of 2 also prefer this conformation. This result experimentally confirms the previously simulated gauche conformational preference of γ in a duplex GNA strand in solution. 20 Regarding the phosphodiester torsion angles δ, ε and β (Figure 1) of 2, both of them adopted the same orientation as that observed in solid state GNA duplexes. 19,20 Torsion angle α was shown to be in a gauche orientation instead of the anti geometry found in solid state GNA duplexes. 19,20 Such favoured g--/g--geometry of ε/α is consistent with the calculated global energy minimum of diethylphosphate in solution.

21

Independently on a possible uncertainty on the geometry of α, it can be concluded that the two thymine residues of 2 are not suitably positioned to photoreact. Concerning the conformation adopted by the hetero diGNA 5, all torsion angles were determined to be similar to those of 2 considering the antipodal chirality of the 3'--end residue. In 5, the two thymine residues were also not properly arranged for UV reaction. This conformational study indicates that the predominant conformation adopted by 2 and 5 corresponds to a state in which the thymine residues are not stacked and the trace CD--detected stacked population corresponds to a very minority stacked conformation that is not suitable to be photoreactive. The lack of thymine stacking in 2 and 5 is fully consistent with their UV robustness. This study also indicates that the strong preorganization reported for the ssGNA backbone 2b already occurs at the GNA TT level. Associated to the conformational analogy between ssGNA and duplex GNA strands,2b,19,20 and to the conformational dependence of PP formation,16e,17,22 this likely suggests that the photochemical behaviour of GNA TT mimics the one of the TT sequence in ssGNA and in duplex GNA. In addition, our results obtained using the most photoreactive sequence indicates high photostability of short ssGNA. However, more tests should be performed to definitively rule out the possibility of formation of C or U photohydrates and PPs in GNA, and to confirm that ssGNA with mixed sequences are indeed photostable.

In conclusion, the replacement of the five--carbon cyclic sugar of nucleic acids by the acyclic chiral three--carbon glycerol moiety in GNA which preserves Watson--Crick base pairing and helicity property is expected to preclude intra-strand photoproduct formation which is an hallmark of modern nucleic acids. We have demonstrated that the photoresistance of GNA TT in aqueous solution is due to the low overlap interaction between adjacent thymine residues. Consequently, GNA may have played a role in the prebiotic emergence of nucleic acids through assembling nucleobases while preserving their remarkably high UV photostability 23 leading to a more robust genetic information storage than do current nucleic acids. However, they may not have participated in the evolution of life due to their impossibility to elicit mutagenic photodamage. Interestingly, the UV stability of GNAs highly contrasts with the UV vulnerability of PNA TT which also possess an acyclic backbone. 24 In this later case, the aminoethylglycine backbone is compatible with intra--strand base stacking overlaps similar to those present in DNA. 25 To our knowledge, GNA would constitute the first UV resistant polymer among promising xeno nucleic acids reported so far. Such distinctive property is highly appealing for challenging nucleic acid application conditions that requires UV light and structural integrity. The ability of GNAs to form nanoshape structures 3a combined to its unique UV stability represent a formidable opportunity for the potential development of photometalized nano structures and phototriggered nanodevices under non--destructive UV conditions.

24,25

Conflicts of interest

There are no conflicts to declare.

Notes and references

  Fig. 2 Structure of TpT 1 and of its four GNA surrogates 2--5. The synthesis of 2--5 made use of the known tritylated thymine glycol nucleosides (R)--6 and (S)--6

14 (

 14 Fig. S25, ESI †). Photoresistance of 2 and 5 was confirmed by 1 H NMR analysis of the crude photoreaction mixture (Fig. S22--S23, ESI †) that remained unchanged. No shielded methyl signals near 1.5 ppm corresponding to the saturation of the C5--C6 double bonds of CPD were observed 15 as observed for TpT 1 (Fig. S24, ESI †). Similarly, no H6 and methyl signals characteristic of the (6--4) PP structure 14 appeared. Photodimerization efficiency of two thymine moieties linked by a sugar phosphate backbone highly depends on their stacking ability.16

  26

Nevertheless, UV light is a well known nucleic acid damaging agent due to photon absorption by nucleobases followed by cytotoxic and mutagenic photoproduct (PP) formation.