J P Allegret
email: allegret@gate.cnrs.fr

Ph Dulbecco
email: philippe.dulbecco@cerdi.u-clermont1.fr

The Institutional Failures of International Monetary Fund Conditionality ♦

The conditionality employed by the International Monetary Fund (IMF) in its lending policy is one of the main themes of controversy in the debate on the new international financial architecture. The purpose of this paper is to propose an analytical framework integrating the diverse explanations of the failure of IMF conditionality. Our analysis is based on the idea that the IMF is a key player in the running of markets in a global economy. More precisely, we explain that most of the criticisms concerning conditionality should be analyzed through what we agree to call the institutional failures of IMF conditionality. These institutional failures must be appreciated at two complementary levels: the first level refers to the intrinsic bureaucratic bias of the IMF while the second deals with the inability of the IMF to manage the institutional change required for the development of market processes and hence to maintain the institutional order in recipient countries. Although the first level failures have been particularly well studied via the international public choice approach, those of the second are, at best, often reduced to a simple statement. However, analyzing both levels of institutional failure of the IMF together is not without implications for the way in which the reforms of conditionality are conceived. Indeed, by including an analysis of the second level of failures, i.e. those relating to the relationship between conditionality and domestic institutional change, the recommendation of ex-ante conditionality emanating from the public choice approach, which tackles the first level of failures, will be invalidated. Instead a new approach will be proposed that suggests the separation of the role of the IMF as financial backer from its role as adviser to countries confronted by the globalization process.

The Institutional Failures of International Monetary Fund Conditionality

Introduction

Conditionality is a central feature of the IMF's activities. Broadly defined, it is "a mechanism that links financing and policies" (IMF, 2001a: 4). Conditionality specifies policies, performance criteria and standards which borrowing countries must satisfy to receive resources from the Fund.

Although conditionality was initially a vaguely expressed concept in the Bretton Woods Agreements, it developed during the 1950s with the expansion of IMF's lending activities, and more particularly after 1979. During the 1980s and 1990s, the IMF was confronted by increasingly complex problems such as the debt crisis of developing countries, the transition of socialist countries to market economies, and the increased influence of global capital markets. Consequently, binding conditions attached to IMF agreements became ever more sophisticated and numerous. "The mean value of the average number of binding conditions for arrangements initiated between 1952 and 1973 was 4.23; between 1974 and 1982 was 7.13; between 1983 and 1990 was 12.07 and between 1991 and 1995/2000 was 12.42" (Gould, 2001: 6) 1 . This trend has been accompanied by two developments.

The first is that the IMF has exerted a growing influence on domestic affairs. The increasing use of procedural conditionality, instead of target conditionality, is a clear illustration of this process. Targets refer to measures -such as a fiscal deficit limit -that can be met by borrowing countries in whatever way they choose. Procedures specify both ends and means by requiring countries to implement a single onetime action, for example a change in exchange rate regime or the adoption of new corporate governance principles. One consequence is that "procedures more directly dictate borrowing country policies, constrain domestic politicians and violate sovereignty" (Gould, 2001: 8) 2 . The second development, as noted by [START_REF] Kapur | Governance-related Conditionalities of the International Financial Institutions[END_REF], is that the IMF has introduced more and more governancerelated conditionality in its programs. The point is that this new form of conditionality implies the need for institutional change in countries under IMF programs. It is a clear departure from the original purpose of conditionality. Indeed, conditionality was initially a tool to protect the financial integrity of the IMF, whose intent is to provide financial resources to member 1 . See also, [START_REF] Goldstein | IMF Structural Conditionality: How Much is Too Much?[END_REF] and IMF (2001a) for statistical data.

2 . After 1982, a steady increase in procedural conditionality can be observed. countries with balance of payments imbalances 3 . With the increasing number of conditions, the IMF has become more and more involved in micro-management whereas, initially, it was focused on its core areas, that is, monetary and fiscal macroeconomic issues. The link between IMF lending and balance of payments problems is increasingly less obvious.

Although conditionality is now at the heart of the IMF's activities, it is also one of the main areas of controversy in the debate on the new international financial architecture. Indeed, even if the IMF were successful in protecting its financial integrity (bearing in mind that this was one of the original purposes of conditionality), the poor completion of IMF programs, lead increasing numbers of observers to stress that conditionality is inefficient4 . The main reasons for such inefficiency are as follows 5 . Firstly, the growing number of monitoring tools used by the IMF renders conditionality too complex and difficult to monitor. The IMF itself admits an "ambiguity about the boundaries of conditionality" (IMF, 2001a: 18). Secondly, the proliferation of conditions, especially structural conditions, makes conditionality too intrusive and costly. As a result, member countries are discouraged from demanding the Fund for assistance. Not only do they contest the political legitimacy of the Bretton Woods institution, but also they wait for a situation to become extreme before resorting to IMF lending. Thirdly, conditionality seems ineffective in inducing policy changes. On the one hand, borrowers do not view the withholding of funds as a credible threat. On the other hand, the effectiveness of conditionality is undermined by difficulties in monitoring compliance. Finally, IMF conditionality suffers from the one-size-fits-all approach. The IMF staff uses best practices and theoretical benchmarks without investing sufficiently in obtaining knowledge of the initial conditions specific to each country, such as domestic political factors and the cultural environment.

The purpose of this paper is to propose an analytical framework forging together these various explanations of the failure of IMF conditionality. Our analysis is based on the idea that the IMF as an institution plays a major role in running the market in the global economy. Indeed, 3 . According to Article I of the Articles of Agreement, one of the purposes of the IMF is "to give confidence to members by making the general resources of the Fund temporarily available to them under adequate safeguards, thus providing them with opportunity to correct maladjustments in their balance of payments without resorting to measures destructive of national or international prosperity". In other words, the original conception of IMF lending was to allow countries to make an adequate trade-off between adjustment and financing. let us recall that the function of any institution is to provide structures that enable players to coordinate their behaviour. Thus institutions provide an essential element for the harmonious functioning of markets. These coordination structures are provided by the IMF to countries engaged in IMF programs, especially through conditionality. Indeed using the mechanism of conditionality, the IMF is implicitly mandated by the international community to push countries that have IMF programs, to implement the institutional reforms and good practices required for participation in the process of market globalisation. Consequently we explain that most of the criticisms addressed at conditionality should be analyzed through what we call the institutional failures of the IMF which, in turn, are a cause of the ineffectiveness of IMF conditionality. These institutional failures must be appreciated at two complementary levels: the first level refers to the intrinsic bureaucratic bias of the IMF while the second deals with the inability of the IMF to manage the institutional change required for the development of market processes and hence to maintain the institutional order in recipient countries.

Although the first level failures have been particularly well studied via the international public choice approach, those of the second are, at best, often reduced to a simple statement.

However, analyzing both levels of institutional failure of the IMF together is not without implications for the way in which the reforms of conditionality are conceived. Indeed, by including an analysis of the second level of failures, i.e. those relating to the relationship between conditionality and domestic institutional change, the recommendation of ex-ante conditionality emanating from the public choice approach, which tackles the first level of failures, will be invalidated. Instead a new approach will be proposed that suggests the separation of the role of the IMF as financial backer from its role as adviser to countries confronted by the globalization process.

The remainder of the paper is structured as follows. Section 2 analyses the ineffectiveness of IMF conditionality from a public choice perspective. The purpose here is to return to the intrinsic institutional failures of the IMF so as to understand the poor completion of IMF programs. Section 3 makes use of the Austrian theory of institutions in order to appreciate the challenge of the institutional change faced by recipient countries. Section 4 concludes our discussion.

The Ineffectiveness of Conditionality: a Public Choice Approach

The institutional dimensions of IMF conditionality have been analyzed using the public choice approach. Indeed according to this line of analysis, the efficacy of IMF programs could be altered by focusing on factors which all refer to the institutional failures of the IMF.

Numerous studies devoted to examining the efficacy of IMF programs highlight, for example, the decisive role of political factors in undermining their success (2.1.). Two other institutional failures are also analyzed: the bureaucratic bias of the IMF on the one hand, and the weak incentives for implementation of conditions on the other (2.2.). The point is that these analyses all point to the need for a specific reform of conditionality based on the idea of pre-conditions (2.3.).

The Influence of Political Factors on Conditionality

Political factors and the efficacy of IMF programs are highly interactive: not only do domestic political factors exert an influence on the completion of IMF's measures, but the IMF is not exempt from taking political factors into consideration when it decides to stop or continue an incomplete program at the end of the initial period of measures.

When considering the interaction between international and domestic institutions to explain the completion of programs, [START_REF] Vreeland | Institutional Determinants of IMF Agreements[END_REF] details the way in which governments may use the IMF's leverage to push through unpopular policies. In a similar vein, [START_REF] Edwards | Sticking with Yes: Domestic Institutions and IMF Compliance[END_REF] demonstrates that the ability of governments to satisfy IMF conditionality depends on the political system; a fractionalized (divided?) legislative political organization will tend to exhibit poorer performance in fulfilling the aims of IMF programs than a united one. [START_REF] Ivanova | What Determines the Implementation of IMF-Supported Programs?[END_REF] use an econometric approach to identify factors affecting implementation of IMF-supported programs. Program implementation is measured with different indicators referring to the extent to which the program has been completed without excessive delays, the extent to which conditions have been met, and the extent to which funds have been disbursed by the IMF. The variables that are likely to influence program implementation are as follows: (i) the political characteristics of borrowing countries, (ii) the variables describing the IMF's behavior during program implementation, and (iii) domestic conditions in countries under programs and external conditions affecting them. The authors study 170 IMF programs over the period of 1992-1996. Their main result is that domestic political factors exert a strong influence on program implementation. Program completion is low in countries with strong special interests, lack of political cohesion, inefficient bureaucracies, and ethno-linguistic divisions6 . [START_REF] Dreher | The Influence of Elections on IMF Program Interruptions[END_REF] stresses the influence of elections on the interruption of programs. Using a sample of 104 countries over the period of 1975-1998, he shows that the frequency of interruption is higher before elections. This is especially the case in more democratic countries where governments need popular support to win elections. Interestingly, the author shows that elections and democracy interact with each other: the influence of elections on program interruptions decreases correspondingly with the degree of democracy. Assuming that non-compliance of conditions is higher before elections in such regimes, due to the unpopularity of the measures associated with IMF conditions, one can conclude that the Fund is probably more lenient towards democratic regimes. Dreher and Vaubel (2004a) suggest that IMF assistance facilitates political business cycles in the recipient countries 7 . According to the authors, IMF lending facilitates a pre-election boom 8 while IMF conditionality is used by domestic authorities to justify post-election recession. According to their results, it appears that monetary expansion and fiscal deficits are larger at the time of elections, and that new net IMF credits are significantly larger immediately before and after elections in democratic countries. Does the strategy implemented by powerful states in the world economy explain the IMF's decisions to interrupt or continue a program with a member state? The answer specified in the IMF's charter is clear: political factors do not exert any influence. Empirical studies are more mixed in their conclusions. In order to explain why countries get financial assistance from the IMF, [START_REF] Barro | IMF Programs: Who Is Chosen and What Are The Effects?[END_REF] suggest that the extent of political connections to the IMF appears to be a significant explanatory variable determining the probability and size of IMF loans 9 . [START_REF] Thacker | The High Politics of IMF Lending[END_REF] studies the underlying causes of the IMF's behavior concerning lending decisions and sanctions when borrower compliance with IMF conditionality is weak 10 . His main result is that politics matter in the IMF and consequently there is no guaranty that the deeper integration of the IMF into the domestic political game leads to better outcomes. The IMF, in its decision-making, does not necessarily follow the general interest of the countries concerned, but instead can be influenced by strategies pursued by powerful states in the world economy. According to [START_REF] Dreher | Independent Actor or Agent? An Empirical Analysis of the Impact of US Interests on IMF Conditions[END_REF], the United States exerts a significant 7 Based on a sample of 106 countries that obtained IMF credit over the period of 1971-1997. 8 . For example, governments can use IMF credits to make foreign exchange interventions in order to sustain the exchange rate regimes after a monetary expansion. 9 . The determinants of the political connections are the following: country quota, the number of nationals amongst the IMF staff, and member country's political and economic proximity to the IMF's major shareholding countries. Each of these determinants exerts a significant influence on IMF loans. 10 . Decisions to lend are analyzed over the period of 1985-1994 for 87 developing countries. influence on IMF conditionality 11 . Not only do closer allies of the US enjoy a lower number of conditions than other countries, but also, prior to elections, it appears that IMF conditionality is softer with governments that support US international strategy.

Overall, the influence of political factors on conditionality raises two issues that pose a challenge for the IMF. The first is that it appears to be increasingly necessary to devote sufficient resources "to identify reformers not to create them" (Dollar, Svensson, 2000: 896).

The second is that the efficacy of IMF conditionality depends in part on the degree of depoliticization of IMF decisions.

The IMF Institutional Failures

Two institutional failures can be distinguished: those arising from the existence of a bureaucratic bias, in which the activities of the institution do not respond to collective needs but to the maximization of its budget; and those based on the weakness of incentive mechanisms within the IMF and between the IMF and the recipient countries.

A potential bureaucratic bias can emerge from the ability of international institutions to become autonomous and to be powerful actors in global politics. Autonomy is based on knowledge of the functioning of the global economy and leads to an expertise, both technical and informational, that is not shared by international institutions with other actors, mainly

states. An illustration of this process is the evolution of conditionality within the IMF. "The development of the principle of conditionality went hand-in-hand with a shift in responsibility from the executive board to the staff" (Martin, 2002: 20).

With the evolution of conditionality, not only does the staff have a significant agenda-setting power, but it also acquires confidential information about the countries' economic situation not transmitted to the executive directors. This evolution constitutes a powerful source of autonomy for the staff. Thus, the staff can use this autonomy to achieve its own preferred objective, that is the maximization of its budget and its size, by changing conditionality over time. The evolution of conditionality is consequently not necessarily linked to changing conditions in the world economy. This hypothesis is confirmed by Dreher and Vaubel (2004b), who explain that the evolution of conditionality seems to be founded not on 11 . 38 countries over the period of October 1997-March 2003 are studied. The relationship between the US and the recipient country is identified through voting in the United Nations generally assembly. The two countries are considered as allies when they vote in the same direction. economic motives, but on the level of demand for IMF credit relative to the IMF quota 12 .

Overall, the staff balances the marginal utility of imposing conditions, that is the safeguard of its financial integrity, with the marginal disutility of losing demand for its credit as a consequence of stronger conditions, that is a decrease in its influence.

Two main incentive failures can be distinguished. The first refers to the decision-making process. At this level, [START_REF] Willett | Towards a Broader Public Choice Analysis of the IMF[END_REF] stresses the dependency of staff members, in terms of their careers, on the IMF management 13 and Executive Board. Political pressures prevent staff members from advising on decisions exclusively founded on economic analysis: IMF lending to Russia is a good example, where political pressures from the major industrial countries led the staff to take decisions that were inefficient from an economic point of view.

But bearing in mind management's control over staff careers, it was rational to promote a loan to Russia.

A second incentive failure within the IMF refers to what [START_REF] Svensson | Why Conditional Aid Does not Work and What Can Be Done About It?[END_REF] has called the "budget-pressure problem". In most donor organizations, there is a discrepancy between allocation and disbursement decisions. Generally, allocation decisions are centralized, and depend on guidelines and procedures, while disbursement decisions are decentralized, and are based on specific projects or countries. Consequently organizations exhibit "a strong bias towards 'always' disbursing committed funds to the ex ante designated recipient, irrespective of the recipient government's performance and the conditions in other potential aid recipient countries" (Svensson, 2003: 383). There is no link between the recipient country's efforts to satisfy conditionality and the disbursement of funds 14 .

The Reforms of Conditionality from a Public Choice Perspective: Tying the Hands of the IMF

The public choice solution to these inefficiencies of conditionality is to tie ex ante the hands of the IMF. Thus, in the spirit of the Advisory Commission [START_REF] Meltzer | International Financial Institution[END_REF], Dreher andVaubel (2004a and2004b) suggest substituting ex post conditionality by ex ante 12 . Their study uses two main statistical sources : a chronological study from 1958 to 1999; an econometric analysis over the period of October 1997-March 2003 for 206 IMF letters of intent concluded with 38 countries. "Conditionality increases when the demand for IMF credit grows relative to quota; (…) conditionality decreases or stagnates when the demand for IMF credit is weak or IMF quotas have been raised" (Dreher, Vaubel, 2004b: 10). 13 . The Managing Director and Deputy Managing Directors. 14 . [START_REF] Svensson | Why Conditional Aid Does not Work and What Can Be Done About It?[END_REF] confirms this result using data from around 200 structural adjustment programs from the World Bank over the period of 1980-1995. conditionality 15 . The main purpose of the latter is to establish the pre-conditions that country members must fulfill in order to be eligible for IMF lending. Pre-conditions reflect the financial soundness of countries, (Meltzer, 2000: 25) that is: (i) the country's commitment to fiscal standards, (ii) a policy of transparency based on the public communication of timely and accurate financial information, (iii) an adequate capitalization of domestic banks, and (iv) authorization for foreign banks to participate in the domestic banking system.

The IMF contingent credit lines (CCL) facility created in 1999 is close to this ex ante conditionality. The CCL facility offers member countries with strong economic policies, a precautionary line of defense against balance of payments problems linked to financial contagion. Countries satisfying pre-conditions could accede to a specified amount of financing automatically available. However since its creation, no country has signed up for pre-approval, and the Executive Board decided not to renew the CCL in November 2003 16 .

Although the IMF justifies such a decision by stressing the reinforcement of the international financial system, it seems that the CCL has suffered a major breakdown. Indeed, the CCL requires that each member country sign in advance a declaration regarding its potential need for IMF lending. The difficulty lies in the fact that the risk exists that such an official declaration may be interpreted as a negative signal by international markets. The reasoning is as follows: by subscribing to the CCL, a government implicitly announces that it anticipates a crisis and a need for IMF credit. This is why Dreher and Vaubel (2004b) defend the idea that all countries should be eligible for such a facility, without a pre-declaration if they respect the pre-conditions. This effective ex ante conditionality requires both an official mandate and a universal principle.

The main advantage of the ex ante condition could be to reduce political pressures during currency crises and thus to enhance IMF credibility. However, for the promoters of this socalled ex ante approach, conditionality should be limited only to short-term credits issued by the IMF during a liquidity crisis.

The public choice approach to conditionality raises two questions (and has two drawbacks).

First, in restricting ex ante conditionality to short term credits, is omits the question of structural conditionality. Despite intense debates about the opportunity to transfer this 15 . [START_REF] Vaubel | The Political Economy of the International Monetary Fund: A Public Choice Approach[END_REF] has made a similar suggestion. 16 . IMF Press Release, no. 03/207, November 26, 2003. conditionality to development agencies (such as the World Bank) 17 , structural conditions remain very important in the programs of the IMF. At present structural conditionality exerts a strong influence on institutional changes in countries under IMF supported-programs.

Second, and more importantly, as we will explain below, both ex post and ex ante conditionality have to deal with the domestic institutional changes accompanying lending to recipient countries. Public choice theory proposes only a partial study of the institutional dimension of IMF conditionality. Indeed, as conditionality inefficiencies are limited to the running of the IMF itself and to the evaluation of the incentives schemes, the public choice view shares the same inconsistency with the IMF when considering the institutional component of conditionality.

We believe that taking into account these institutional changes is a necessary condition for understanding the circumstances required for improved intervention on the part of the IMF.

Contrary to what the Advisory Commission has said, such analysis will not lead us to a rejection of any kind of long-term structural conditionality on the part of the IMF18. On the contrary, this type of conditionality is useful in promoting structural reforms in developing countries in order to enable them to adapt their economies to the globalization process. The problem for the IMF then is not only one of modifying the incentive mechanisms, but also of considering what reforms might be suitable given the subsequent process of domestic institutional change foreseen. From this perspective, structural conditionality does not necessarily need to be tied to lending. The following section is dedicated to this issue.

Towards an Austrian Theory of IMF Conditionality Failures

In any explanation of economic development as well as of the difference in performance of economies over time, the importance played by institutional change is scarcely controversial. [START_REF] Rodrik | Growth Strategies[END_REF] (North, Weingstat 1989). More precisely even if growth without good institutions might be possible, sustainable growth requires major institutional change along with the implementation of institutional functions the objectives of which are to create, regulate, stabilize and thus legitimize markets [START_REF] Rodrik | Growth Strategies[END_REF]. Having established this point, however, it begs the question as to how such a goal can be reached especially in low-income countries. The question has aspects sides to it. The first refers to the financial capacity of countries to invest in their institutional architecture. The second refers to the implementation 17 . As suggested, among others, by the Advisory Commission. process itself. Here, IMF conditionality is required to play a major role. This section thus returns to the issue of the structural conditions attached to IMF programs. Drawing on the Austrian perspective concerning the critical role of institutions in the market process, we explain why conditionality may jeopardize the institutional order of recipient countries (3.1). This analysis leads us to criticize traditional proposals for the reform of conditionality (3.2).

Alternative proposals are made for improving conditionality. The cornerstone of these proposals consists of redesigning the relationship between the recipient countries confronted by the need for major institutional changes, and the IMF. Such an evolution implies a transformation of the role of the IMF. (3.3).

Institutions, Institutional Changes and Conditionality

Let us recall that an institution is usually defined as "a regularity in social behavior that is agreed to by all members of society, specifies behavior in specific recurrent situations and is either self-policed or policed by some external authority" (Schotter, 1981: 11). This definition requires consideration not only of the legal framework, but also of regular behavioral practices associated with a set of rules, norms and routines. These two elements may influence both the emergence and evolution of institutions.

Institutions also represent a means by which agents, who are ignorant of each other's actions and expectations, obtain information that enables them to co-ordinate with each other. In other words, they represent nothing more and nothing less than a necessary condition for the running and development of markets [START_REF] O'driscoll | The economics of time and ignorance[END_REF] 19 .

Modifying the institutional structure of any economy is consequently not only complex but likely to induce some profound and not necessarily foreseen or appropriate economic changes. This is the case when implementing conditionality. Structural conditionality imposes domestic institutional changes. This is so even though the IMF has tried to reduce the number of structural conditions in its new programs. The structural benchmarks (SBMs) that focus on qualitative indicators, going beyond the traditional quantitative indicators of the IMF, have 18 . Adopting a different perspective, [START_REF] Willett | The IMF and Capital Account Crises: The Case for Separate Lender of Last Resort and Conditionality Functions[END_REF] suggests separating IMF programs into two major categories: a short-term facility with ex ante conditionality, and structural conditionality. 19 . This argument naturally rests on the idea that the knowledge disseminated by institutions is of a stabilizing nature, in that it reaffirms the stability of the social structure at regular intervals, unlike that disseminated by the price system, which is of a dynamic nature in that it leads individuals to revise their plans continually [START_REF] Hayek | The use of knowledge in society[END_REF]. followed the same development (IMF, 2001a) 20 . More fundamentally, it is increasingly obvious that every IMF action, the main intent of which is to obtain macroeconomic equilibrium, is never without consequences with respect to the institutional structure of a recipient country, even if the IMF tries to concentrate the majority of structural conditions on a relatively small number of sectors 21 .

The analysis of structural conditionality thus requires that we specify the conditions required for the recipient country's institutional order to have coherence. More precisely, such analysis must enable us to solve three interrelated problems.

Firstly, we formulate the issue of the institutional order and its unity. If the complementarity of institutions is what builds the institutional order of a society, the purpose then is to identify the forces that encourage integration, as well as the circumstances under which these forces cease to work. The distinction between 'designed institutions' and 'undesigned institutions' [START_REF] Lachmann | The legacy of Max Weber[END_REF] is crucial here. The former, which include legal norms, are "the products of legislation and other manifestations of the 'social will'" (Lachmann, 1970: 69), while the latter are spontaneous entities, understood as "recurrent patterns of conduct" (ibid.: p.75).

According to Lachmann's logic, while not all institutions assume the same status and function, they do, nevertheless, share the attribute of flexibility linked to the permanency of the whole. The matter now arising is how to make institutional change and structural permanence compatible, as it is not so much the change per se which gives rise to problems here, but rather unexpected change 22 . Conditionality should not be implemented without 20 "SBMs are indicators which aim to delineate the expected path of reform for individual structural policy measures and that can facilitate the evaluation of progress for these actions. Because many structural policies cannot be expressed in quantitative form, structural benchmarks are usually expressed qualitatively; for example, if the program calls for privatization of the state-owned telephone company, submitting the privatization bill to the legislature by date x could be one structural benchmark. Failure to meet structural benchmarks conveys a negative signal but does not automatically render a country ineligible to draw; instead, a decision about eligibility would be judgmental and would likely be made in a broader mid-year program review -itself an instrument of conditionality-with an eye toward the country's overall progress on the structural front" (IMF, 2000c).

21 "The majority of structural conditions -between a half and two thirds-have been, and continue to be, concentrated in a relatively small number of sectors that are at the very core of the Fund's involvement in member countries: exchange and trade systems, and fiscal and financial sectors. The relative importance of these sectors has changed, with reforms in the exchange and trade system now playing a smaller role and the financial sector a more important one than in the early 1990s. In addition, public enterprise restructuring and privatization -in part motivated by fiscal considerations-have accounted for about one fifth of the structural conditions in Fund-supported programs. Nevertheless, while a large part of structural conditionality has focused on a relatively small number of sectors that are closely linked to stabilization and external adjustment, this does not guarantee that structural reforms have always been adequately prioritized nor does it imply that too broad a reform agenda has never been an issue" (IMF, 2001a). 22 . Only this latter type of change is likely to disrupt some plans in the course of action.

taking into account its effects on institutional complementarity, that is on the institutional order of the affected country.

Secondly, the distinction between induced and imposed institutional change [START_REF] Lin | An Economic Theory of Institutional Change: Induced and Imposed Change[END_REF]) must be considered. An induced institutional change refers to the modification or replacement of an existing institution or the emergence of a new one that is voluntarily initiated and executed by an individual or a group of individuals in response to profitable opportunities. An imposed change, in contrast, is introduced and executed by an authority following its own rationale.

The main point here is that institutional changes accompanying the IMF's programs are often imposed and rarely induced. The consequence is that conditionality may be conducive to a deterioration of agents' economic performances compared with the initial situation.

Thirdly, we must not forget that institutional change takes time. Indeed, the transformation of existing institutions, as in the creation of new institutions, is subject to delays: delays of implementation in the first instance, and delays of construction in the second. Yet the amount of economic change possible per unit of time is always limited because agents have limited training capacities. Indeed, given a theoretical or practical scenario, in which an economic or political authority -in this case the IMF-decides to put into place new institutions, via conditional Fund-supported programs, the benefits expected from this type of measure are debatable. The reason is that, insofar as such a policy is, by definition, limited to designed institutions, its success depends on the capacity of these new elements to meet the demand for change in institutions not yet designed. The difficulty lies in the fact that, although the transformation of designed institutions is, in general, both radical and speedy, that of nondesigned institutions is of an incremental nature and is necessarily subject to path-dependent constraints. "Various institutions and social expectations change at different speeds, particularly when there is a mix of exogenous and endogenous forces, as when global markets interact with domestic policies [...].The central problem to be addressed […] is variable institutional adaptation" (Jacobs, 1999: 8). Yet in all cases, the time horizon of any structural program, that is the time horizon of conditionality, is radically different from that necessary for implementing the required institutional change.

Solving these three issues comes down to providing a solution to the so-called permanencyflexibility dilemma that any emerging and low-income economy faces. The issue is thus how to make institutional change and structural permanence compatible. Even if not all institutions assume the same status and function, they all share the attribute of flexibility linked to the permanency of a whole. The permanence of the overall institutional order does not involve the permanency of each part. But how can the need for coherence and permanence be reconciled with the need for flexibility, especially for low-income countries? The potential solutions are of primary importance in indicating what the role played by the IMF should be, more precisely in pointing to a transformation of its role beyond that of imposing so-called ex ante conditionality.

Reform of Conditionality : A Critical Review of Traditional Solutions

Proposals relating to the reform of conditionality focus on the necessity of strengthening the ownership of programs. This is a result of the strong correlation between successful completion of measures and the degree of ownership 23 . Ownership is a multidimensional concept (World Bank, 1992). First, it refers to the extent to which planned reforms in programs have been locally or externally initiated. Second, it is based on the idea that intellectual conviction as to the appropriateness of measures, matters. Finally, the degree of support from top political leadership appears to be a determinant of ownership24 . Two complementary approaches to conditionality reform aim to strengthen ownership.

The first approach establishes that the efficacy of conditionality could be improved by means of a more flexible approach 25 . Some critical of IMF-programs consider that the penalties attached to the current conditionality are unsatisfactory. In principle, a program that has failed to be completed is penalized based on what the initial overall measures agreed to have been.

Thus, implicitly, the relationship between the IMF and the recipient countries follows a "takeit-or-leave-it" logic. Such a penalty scheme lacks flexibility if one considers the obligation that a country comes under to implement both macroeconomic adjustments and structural reforms. In effect, waivers introduce a degree of flexibility into IMF-programs. Under this scheme, the IMF agrees not to interrupt a program, even in cases of non-observance of performance criteria, if it considers that the program will eventually be successfully implemented. Under these circumstances, IMF-supported programs could be considered dynamic and flexible. But, as stressed by the IEO (2005b), flexibility linked to waivers is not necessarily a satisfactory situation, but rather reflects "unrealistic expectations" (IEO, 2005b: 23 . Numerous empirical studies have established this relationship. See [START_REF] Collier | Report of the Group of Independent Persons Appointed to Conduct an Evaluation of Certain Aspects of the Enhanced Structural Adjustment Facility[END_REF]. 10). A more genuinely flexible procedure could be one based on a disaggregated reform package and a floating tranche. In this vein, [START_REF] Leandro | Towards a More Effective Conditionality: An Operational Framework[END_REF], and in a similar approach Collier et al. (1997), propose to divide reform packages into several reform areas, each of them being the object of specific conditionality and monitoring. The aim is to be able to devise a penalty that is more proportional to the initial lapse in implementation. The floating tranche approach, supported by [START_REF] Khan | IMF Conditionality and Country Ownership of Programs[END_REF], would allow each country to implement structural reforms at their own speed without putting the receipt of funds into question if a section of reforms has or has not been completed. The proposal is that the IMF would disburse credits (called floating tranches) in proportion to the adoption of structural reforms specified in the initial agreement. But only the usual quantitative performance criteria would be the object of conditionality.

Furthermore, the development of a flexible approach implies that the IMF would need to be engaged in intensive and informal policy dialogue with the recipient country. The views of government, political leaders, trade unions and members of civil society would all need to be taken into account. As explained by [START_REF] Collier | Report of the Group of Independent Persons Appointed to Conduct an Evaluation of Certain Aspects of the Enhanced Structural Adjustment Facility[END_REF], the IMF has to develop "a more systematic mechanism for providing ex post support for country-initiated, or home-grown, programs" (p.22). Three implications are inferred from this new strategy. First, resident missions in recipient countries could have more authority. Second, the IMF should allocate more resources and time in order to improve their understanding of countries' political constraints. Finally, a greater degree of initiative could be given to domestic authorities during the negotiation of the program in order to give the process more credibility, implying the need for more flexible behavior on the part of IMF staff 26 .

A second approach, adopted by the IMF, is to streamline structural conditionality. Taking into account the poor performance of its recent programs, the IMF is trying to reduce the number 25 . A detailed presentation of this approach is beyond the scope of this paper. See, among others: [START_REF] Leandro | Towards a More Effective Conditionality: An Operational Framework[END_REF]; Collier et al. (1997); [START_REF] Collier | Report of the Group of Independent Persons Appointed to Conduct an Evaluation of Certain Aspects of the Enhanced Structural Adjustment Facility[END_REF]; [START_REF] Khan | IMF Conditionality and Country Ownership of Programs[END_REF]. 26 . In 1999, the IMF and the World Bank initiated the Poverty Reduction Strategy Papers which give a greater degree of initiative to governments in low-income countries. Indeed, PRSPs are prepared by governments according to a participatory process involving domestic stakeholders. A PRSP describes the macroeconomic, structural and social policies and programs adopted by a country for several years (IMF 2003a). In August 2006, 78 countries were eligible for the poverty Reduction and Growth Facility. The last IMF available review [START_REF] Lombardi | The IMF's Role in Low-Income Countries: Issues and Challenges[END_REF] shows that 49 full PRSPs have been circulated to the Fund Executive Board and an additional 11 countries have completed "interim" PRSPs. Although it is too early to evaluate them, preliminary assessments have stressed the participatory gap after the adoption of the programs and the conflicts between their multiple objectives, revealing the difficulty in adopting a clear priority order. For an external evaluation of PRSP, see [START_REF] Killick | The 'Streamlining' of IMF Conditionality: Aspirations, Reality and Repercussions[END_REF] and I.E.O (2005a); for an internal evaluation, IMF (2003b).

of structural conditions reform in order to concentrate its attention on structural reforms that are "critical" to the achievement of macroeconomic targets. The new conditionality guidelines follow three principles. First, IMF conditionality has to cover structural conditions which are "critical" to the success of the program's macroeconomic objectives. Second, structural reforms, which are not critical but "relevant" to the program's macroeconomic objectives, and which, at the same time, fall within the IMF's core areas, can possibly be subject to conditionality. Finally, conditionality would not apply to structural reforms which are not critical and fall outside the core areas of the IMF's responsibilities, even if they were macrorelevant. Here, the main difficulty is to define the threshold of what is considered critical.

According to the IMF, "critical importance means that excluding the condition would seriously threaten the achievement of the program's goals or the Fund's ability to monitor implementation […]. Determining which measures are critical is inherently an element of judgment" (IMF, 2003a). In the IMF review of the 2002 Conditionality guidelines (IMF, 2005a), two main trends are revealed. On the one hand, the share of structural conditions in non-core areas fell by 17-18 percentage points in both GRA-supported programs and PRGFsupported programs. On the other hand, while PRGF-programs exhibit a significant decline of the average number of structural conditions (from 17-18 to 13-14 percentage points in the late 1990s), in GRA-programs this average number instead increased in recent years. These results indicate "substantial differences between the aspirations of the Fund's management and the actual changes so far achieved" (Killick, 2002: 2). They reflect also the ambiguity and imprecision of the IMF targets due to divisions inside the Executive Board as to how far the reduction in structural conditionality should go. The staff has taken advantage of these divisions to resist the streamlining of the conditionality process (I. E.O., 2005b).

Even if all the previous approaches might represent progress in improving IMF conditionality, they are not necessarily an appropriate response to the problem of institutional change implied by structural conditionality. The main challenge consists in responding to new concerns encountered as a result of the globalization of markets, mainly through ensuring compatibility between domestic and global goals. Indeed, globalization goes hand in hand with the standardization of market processes. And, as we have explained, the IMF becomes a key player in such a process with its new function of facilitating the development of markets in developing countries in accordance with both global standards and domestic constraints.

A new Form of Conditionality

The difficulty consists in the IMF developing its actions around two complementary temporal horizons. The first, encompassing crisis management as well as prevention, requires shortterm actions using traditional tools such as emergency lending and macroeconomic conditionality. Here one finds the IMF in its traditional role, i.e. that of financial backer, and hence with this, the traditional concept of conditionality. The second refers rather to a medium and long-term horizon implying action oriented towards development issues, such as the development of market processes. This second horizon requires the IMF to develop its mandate as adviser to countries confronted by the globalization process. Here, institutional factors play a crucial role. The point we are making, however, is that, when not explicitly taken into account, these two functions may contradict one another. The confusion arising between the requirements of these two horizons is especially relevant in two situations: when member countries are confronted by financial crises on the one hand; and when institutional weaknesses are significant in countries under IMF-programs on the other hand.

The Asian crisis is a striking example of the first situation. In 1997, the IMF concluded unprecedented emergency lending agreements with Thailand (August, $ 17 billion), Indonesia (November, $ 35 billion) and Korea (December, $ 57 billion). These agreements had a similar basic design. This consisted of a mix of traditional conditionality, based on loans to the central bank and government for the repayment of debts and the stabilization of exchange rates, and on a macroeconomic framework promoting restrictive fiscal and monetary policies.

At the same time it included structural conditionality focusing on a restructuring of the financial sector and on good governance measures (transparency, dismantling of monopolies, elimination of directed lending, growing role of financial markets). According to the IMF, this strategy was appropriate in order to re-establish confidence in the financial markets 27 . Indeed, the Fund considered that the vulnerabilities of the financial and corporate sectors were attributable to governance and market discipline deficiencies. In fact, the main purpose of the strategy was to transfer governance principles long adopted in Western advanced economies.

However, these programs were not only ineffective in preventing exchange rate depreciations, but they also exacerbated instability [START_REF] Radelet | The East Asian Financial Crisis: Diagnosis, Remedies, Prospects[END_REF]. In a crisis situation, and subsequently within a very short-term horizon, structural conditions imposed by the IMF, 27 . For instance, see [START_REF] Lane | IMF-Supported Programs in Indonesia, Korea and Thailand[END_REF]; [START_REF] Baliño | Financial Sector Crisis and Restructuring: Lessons From Asia[END_REF].

particularly after the Asian crisis, were aimed at profoundly modifying the domestic institutions of economies thereby provoking economic destabilization.

Countries where rule of law and institutional quality are the weakest often belong to the category of low-income countries28 . The IMF (2004) recognizes four areas of work with lowincome member countries: (i) policy advice; (ii) capacity building; (iiii) financing and debt relief; and (iv) implementation of the Millennium Development Goals (through the Monterrey Consensus). Capacity building is especially important for our purposes. The IMF uses different tools in order to strengthen the institutional architecture in low-income member countries [START_REF] Hakura | The Millennium Development Goals, the Emerging Framework for Capacity Building, and the Role of the IMF[END_REF]. The report of the observance of standards and codes (ROSCs) allows the IMF to promote the adoption of standards in 11 areas grouped into three categories: (i) transparency standards; (ii) financial sector standards; and (iii) market integrity standards for the corporate sector. IMF staff members work with domestic authorities to identify financial sector vulnerabilities and to provide technical assistance through the financial sector assessment program (FSAP).

Whatever the situation -financial crisis or institutional weakness-the IMF structural conditionality suffers from the same drawback: the "one-size-fits-all" approach consisting of transplanting the institutional architecture of mature countries to emerging and developing countries. This approach contradicts recent lessons suggested by the literature on the impact of reforms on growth29 . [START_REF] Rodrik | Growth Strategies[END_REF] stresses that "principles such as appropriate incentives, property rights, sound money, and fiscal solvency all come institution free […]. There may be multiple ways of packing these principles into institutional arrangements". For example, China has experimented with a heterodox way of achieving the above principles, while Latin American countries have adopted the Washington Consensus principles based on an orthodox concept. In terms of growth performances, the two groups of countries have experienced contrasting outcomes: a strong performance for China, but poor for Latin American countries.

In an empirical study, [START_REF] Berkowitz | Economic Development, Legality, and the Transplant Effect[END_REF] show the inefficiencies engendered by the transplantation of formal legal frameworks originating in Western countries to other countries. The I.E.O. (2005c) stresses that the effectiveness of the technical assistance provided by the IMF "has been undermined by a lack of awareness of institutional, organizational, or managerial features of the recipient country" (p.11). Financial reforms in emerging markets underestimated the weight of asymmetric information in such economies.

In this context, banks play a major role to favor the development of contractual practices [START_REF] Allegret | Financial Liberalisation and Stability of the Financial System in Emerging Markets: the Institutional Dimension of Financial Crises[END_REF]. When the international financial institutions promote financial liberalization, it is necessary to bear in mind the fact that such measures alone cannot lead to new financial systems in which market mechanisms are expected to play an important role. The implementation of new legal regulations by authorities does not necessarily lead to the acquiescence of institutions. Indeed, they must be adopted by private agents. In other words, promoting banking reforms, in which the main objective is to encourage banking practices in emerging economies that will converge with practices adopted in numerous mature markets, is not necessarily the most efficient way to promote economic growth. Interpersonal relationships are less prominent in developed countries because of the presence of liquid financial markets with strong legal rules and contract-enforcement mechanisms. Overall, empirical findings confirm our analytical framework: institutional reforms are part of a long-term process that must take into account specific domestic circumstances. Successful reforms must be country-specific and not based on a global and uniform concept of the working of the market economy.

What are the implications for the conduct of IMF structural conditionality? The IMF has to resolve two difficulties in its interventions in developing countries. The first is the time horizon of its policies. On the one hand, structural conditionality requires a long-term perspective with delays in reform implementation and path dependency constraints. On the other hand, IMF lending is by nature short term, focused mainly on 3 year programs. These timings are not compatible with each other. Second, the confusion between its two functionspolicy adviser, especially on matters of institutional reforms, and financial backer-is subject to conflicts of interest, which undermine IMF efficacy. In order to strengthen the effectiveness of the IMF, it seems to us necessary to disentangle these two functions and allow IMFsupported programs including structural conditionality to have longer time horizons. From this perspective, a reform of conditionality should proceed along two main steps. The first is a general application of the policy support instrument (PSI). This new instrument allows member countries to benefit from IMF staff advice without Fund financial assistance. The main purpose of the PSI is "to help low-income countries members in designing and pursuing policies that meet high standards, and to signal the strength of these policies" (IMF, 2005h: 5). Policy dialogue between the Fund and member countries is more intense and frequent under this arrangement than with the Article IV consultations framework. The PSI is based on the member's poverty reduction strategy and includes areas such as financial sector reform, transparency, and strengthening institutions. At present, PSIs are exclusively dedicated to "mature stabilizers", i.e. to countries who don't need IMF assistance 30 . Furthermore, the duration of these programs remains too short 31 with regard to the objectives of institutional reform that they contain. It seems to us that the Policy Support Instrument should be generalized to all developing countries involved in IMF-programs in which institutional reform is implied. A second step in the reform of IMF conditionality is to endow the IMF with tools that would allow it to take better account of the specific domestic circumstances of every member country. In 2004, the IMF created a new instrument for low-income countries that emphasizes the distributional impact of major macroeconomic and structural reforms: the Policy and Social Impact Analysis. We propose to create a similar instrument focusing on the institutional impact of IMF-programs.

Conclusion

In this paper, we have stressed the failures of IMF conditionality, focusing on structural conditionality. The IMF must build a new approach to structural conditionality in order to safeguard the coherence of the institutional order in recipient countries. Conditionality implies institutional change and institutional change is a very complex process which cannot be managed through so-called ex ante conditionality. An alternative solution should not consist of rejecting such change but rather, dealing with its complexity and diversity head on. The analytical framework proposed should help to evaluate both the institutional component of conditionality and the necessary evolution of the role of the IMF. Indeed we suggest a separation of the role of the IMF as financial backer from its role as adviser to countries confronted by the globalization process 32 . From our perspective, the role of the Fund could be (taken over by?? Presumably there is no one to take over the lending role of the IMF but external advisers or consultants could take over the advisory role that IMF staff currently play?) that of an external adviser or consultant in order to take into account the specific circumstances of each country in a global context. By global context, we refer to the new constraints implied by the globalization process that tend to impose a standardized set of behaviors. The evolution of conditionality proposed in this paper would imply that each 30 . Nigeria has been the first IMF-member to use PSI in October 2005. 31 . The duration is between one year and three years with a maximum of four years. 32 . [START_REF] Bevan | The IMF and Low-Income Countries[END_REF] voices several doubts regarding the traditional link between policy advice and financing. Such a separation could apply to the World Bank too. On World Bank conditionality, see [START_REF] Dreher | A Public Choice Perspective of IMF and World Bank Lending and Conditionality[END_REF]. country benefiting from the advice of the IMF should find the best trade-off between the specific characteristics of the domestic institutional order and the global market. This is for us the main challenge of globalization: that is to build coherence between global governance and domestic objectives.

[START_REF] Mussa | The IMF Approach to Economic Stabilization[END_REF], for example, studied 615 IMF arrangements over the 1973-1997 period using a sample composed of

industrial countries and 121 developing countries. Their main result was that more than a third of IMF programs ended with disbursements of less than half of the support initially agreed to. An extensive empirical literature confirms this poor completion of IMF programs.5 . See[START_REF] Goldstein | IMF Structural Conditionality: How Much is Too Much?[END_REF] and[START_REF] Dreher | IMF Conditionality: Theory and Evidence[END_REF] for an overview.

. Studying

developing countries between 1975developing countries between and 1999developing countries between , Joyce (2003) ) shows that successful program implantation is affected by domestic political considerations, notably the degree of democracy, the degree of election competitiveness and the degree of political pluralism.

. IMF defines ownership as follows: "ownership is a willing assumption of responsibility for an agreed program of policies, by officials in a borrowing country who have the responsibility of formulating and carrying out those policies, based on an understanding that the program is achievable and is in the country's own interest"(IMF, 2001b: 6).

. For an overview of the relationship between low-income countries and IMF, see for instance[START_REF] Lombardi | The IMF's Role in Low-Income Countries: Issues and Challenges[END_REF];[START_REF] Martin | A Changing Role for the IMF in Low-Income Countries[END_REF].

. See the recent World Bank study(World Bank, 2005) and[START_REF] Rodrik | Goodbye Washington Consensus, Hello Washington Consensus?[END_REF].


Virus Yinshan Yang

Vianney Poignavent

François-Xavier Gillet

Florence Vignols

Hélène Déméné

NMR chemical shift backbone assignment of the viral protein P1 encoded by the African Rice Yellow Mottle

Keywords: RNA silencing, viral suppressor, cysteine rich, RYMV, P1, sobemovirus RYMV, Rice Yellow Mottle Virus, RNA -Induced Silencing Complex, RISC, siRNA, Small Interfering RNA, VSR, virus silencing repressor

RNA silencing describes a pan-eukaryotic pathway of gene regulation where doubled stranded RNA are processed by the RNAse III enzyme Dicer or homologs. In particular, plants use it as a way to defend themselves against pathogen invasions. In turn, to evade the plant immune response, viruses have developed anti-RNA silencing mechanisms. They may indeed code for proteins called "viral suppressor of RNA silencing" which block the degrading of viral genomic or messenger RNA by the plant. The Rice Mottle Virus is an African virus of the sobemovirus family, which attacks the most productive rice varieties cultivated on this continent. It encodes P1, a cysteine-rich protein described as a potential RNA silencing suppressor. P1 is a 157 amino-acid long protein, characterized by a high propensity to aggregate concomitant with a limited stability with time in the conditions used in structural studies. To overcome this problem, shorter fragments were also studied. This strategy enabled the assignment of more than 90% backbone resonances of P1. This assignment should set the base of future NMR investigation of the protein structure and of its interactions with rice cellular partners.

Biological context.

Rice occupies a central place in the diet of many people in Africa and Asia. Rapid population growth and food habit changes result in an increasing demand, while the rice is very susceptible to pathogen attack. Among these is the Rice Yellow Mottle Virus (RYMV) in the African continent, the infection thereof generates crop losses ranging from 20 to 100%. Like many other plants when confronted with pathogens, rice has evolved an immunity response under the form of viral silencing. Viral silencing represents an essential defense mechanism in plants [START_REF] Ding | Antiviral Immunity Directed by Small RNAs[END_REF]. In short, plants can initiate the degradation of viral double stranded RNA, either genomic or messenger, by processing them with Dicer-like RNAses III into Small Interfering RNAs (siRNAS). Those are recruited in the multi subunit RNA-induced Silencing complex (RISC), which targets them to nuclear or cellular viral RNA for destruction. To counteract host RNAi antiviral defense, viruses from almost all plant virus genera (and also from some animal viruses) encode viral suppressors of RNA silencing (VSRs) which inhibit key steps of the cellular siRNA system [START_REF] Song | Silencing suppressors: viral weapons for countering host cell defenses[END_REF]. They are often multifunctional and play also important roles in viral replication, coating, movement, and pathogenesis. We and others have proposed that the P1 protein of RYMV belongs to this class based on its importance for viral particle spread in rice [START_REF] Siré | Genetic diversity and silencing suppression effects of Rice yellow mottle virus and the P1 protein[END_REF] and on its ability to counteract GFP silencing in a plant reporter system (Voinnet et al., 1999).

The P1 protein is a 157 amino acid long protein, characterized by the presence of numerous cysteines (7) and histidines (6). Biochemical analyses have already revealed important properties of P1, including its capacity to bind two zinc atoms [START_REF] Gillet | The RYMV-Encoded Viral Suppressor of RNA Silencing P1 Is a Zinc-Binding Protein with Redox-Dependent Flexibility[END_REF]. Further structural analyses would help in deciphering how P1 molecular features support its potential functions. However, the protein is insoluble when produced in a culture medium with a zinc concentration below 100 M [START_REF] Gillet | The RYMV-Encoded Viral Suppressor of RNA Silencing P1 Is a Zinc-Binding Protein with Redox-Dependent Flexibility[END_REF] and its structure has never been reported. As a first step towards solving the P1 solution structure and investigating its potential interactions with rice cellular components (proteins or nucleic acids), we report here its sequence specific backbone and some side chain assignments.

Methods and experiments

Protein production and purification

Construction of P1 clones has been previously described [START_REF] Gillet | The RYMV-Encoded Viral Suppressor of RNA Silencing P1 Is a Zinc-Binding Protein with Redox-Dependent Flexibility[END_REF]. Full-length P1 (here termed FL P1), and its truncations P1_1-100 and P1_102-157 (comprising the segment from Met1 to Gln100 and Arg102 to Phe157, respectively) were expressed in E. coli BL21 (DE3) cells using M9 minimal medium supplemented with 1 g/L 15 NH 4 Cl, 2 g/L -1 13 C-D-glucose, 1 mg/L thiamine and biotin and 450 M/L ZnSO 4 at 37°C. Expression was induced by addition of 0.5 mM isopropyl--D-thiogalactopyranoside (IPTG) when an OD 600 0.6 was reached. Cells were then subjected to a thermal shock for 2 hours at 6°C, before further induction during five hours at 30 °C for FL P1 and 20°C for P1 P1_1-100 and P1_102-157. With this protocol, P1_1-100 and P1_102-157 were produced as soluble proteins whereas FL P1 accumulated as inclusion bodies. Proteins were then purified as described in [START_REF] Gillet | The RYMV-Encoded Viral Suppressor of RNA Silencing P1 Is a Zinc-Binding Protein with Redox-Dependent Flexibility[END_REF], except that lysis buffer (LyB 50 mM Tris pH 8, 150 mM NaCl, 1 mM Zn, 1 mM DTT) for FL P1 contained 6 M urea to dissolve the inclusion bodies. After lysis by sonication (and dialysis against 2 L of LysB for FL P1), BL21 supernatant was loaded onto 1 mL of Q-Sepharose Fast Flow pre-equilibrated with buffer A (50 mM Tris-HCl, pH 8.0, 1 mM DTT). P1 constructs were eluted with buffer B (buffer A + 1 M NaCl). The Zn 2+ content of eluted fractions was estimated by the photometric monitoring of Zn 2+ release induced by 4-(2-pyridylazo) resorcinol (PAR) which complexes zinc [START_REF] Gillet | The RYMV-Encoded Viral Suppressor of RNA Silencing P1 Is a Zinc-Binding Protein with Redox-Dependent Flexibility[END_REF]. Fractions where a maximal amount of Zn was present, were pooled, dialyzed against buffer A, and reloaded onto the Q-Sepharose Column. The repeat of this step was essential to obtain a clear separation of the different redox forms. Elution fractions containing P1 bound to the maximal amount of Zn 2+ , were again pooled and loaded into a Superdex 75 Hiload 26/60 column (GE Healthcare) equilibrated with buffer C (25 mM Tris-HCl, pH 7.5, 200 mM NaCl, 1 mM DTT, and 500 μM ZnSO 4 ). The purified proteins were vaccuum concentrated and kept at 4 °C until use. Just before their use for NMR, the buffer was exchanged by dialysis against 100 mM NaCl, 60 mM Na 2 SO 4 , pH8, 500 M ZnSO 4 , 1 mM DTT as stability studies by thermal shift assay showed that sodium sulfate has a net stabilizing effect.

NMR spectra

All NMR experiments were performed at 300 K on a Bruker Avance III spectrometer (Bruker, Rheinstetten, Germany) operating at 1 H frequency of 699.97 MHz, using a 5 mm cryogenic H/ C/N/D probe with Z-axis gradient. Proton chemical shifts were referenced with respect to DSS and the frequency ratios of 15N / 1 H = 0.101329118 and 13 C/ 1 H = 0.251449530 (Wishart et al. 1995). Assignment of the spectrum of P1 was carried out using a dissection approach. NMR spectra were collected for the full-length P1, but also for the shorter proteins P1_1-101, and P1_102-157. These two fragments were chosen on the basis on our previous study and on ongoing work, which characterized them as likely to contain a zinc finger each [START_REF] Gillet | The RYMV-Encoded Viral Suppressor of RNA Silencing P1 Is a Zinc-Binding Protein with Redox-Dependent Flexibility[END_REF].

Protein concentration was 200 M (P1_1-100 and FL P1) and 2 mM (P1_102-157). Initial sequential backbone assignments were obtained with data from 3D C with 3D HNCA, HNCACB, CBCA(CO) NH, (H)CCH-TOCSY and HNCO for FL P1. Gifa was used for NMR data processing [START_REF] Pons | Gifa V. 4: A complete package for NMR data set processing[END_REF] and NMRView for subsequent analysis [START_REF] Johnson | NMR View: A computer program for the visualization and analysis of NMR data[END_REF] NMR assignment and deposition FL P1 contains 157 amino acids encompassing 5 prolines. Its behaviour in solution was characterized by a poor solubility and a high propensity to aggregate within hours. Furthermore, the best determined solubility and stability conditions required a high ionic force, greater than 200 mM, and a high pH (>= 7.5). These conditions are known to diminish the sensitivity of NMR experiments, in particular those where the amide proton is detected during acquisition. Even in these optimized conditions, we observed an apparent loss of sensitivity of 30%-60% within 3 days, depending on the preparation, presumably because of protein aggregation. Most of the missing resonances belong to contiguous segments of the N-terminal part of P1: 12-13, 15-16, 32-34, 61-68, suggesting that the concerned segments are exposed to solvent or subjected to conformational exchange. For the C-terminal segment, only Ser131 and Gly147 could not be assigned. For Ala16, even if the N and HN resonances could not be retrieved, we were able to assign its C and C carbon resonances on the HCCH-TOCSY experiment, after all other alanine spin systems were assigned. The lowsignal/over noise ratio precluded unambiguous further assignment. Altogether, these results allowed us to assign 92 % of N, HN,Ha,C,C and C resonances (fig. 1). This percentage increases to 94.6% for the HN and N resonances, i.e. 142 backbone cross-peaks could be assigned on the 1 H-15 N HSQC spectrum, of the 150 expected (considering the presence of 5 prolines and the absence of cross-peak for the first residue). In addition, all amide 15N and HN resonances of the 6 Gln and Asn side chains could be assigned. Chemical shifts were analysed using TALOS-N to identify regions of secondary structure [START_REF] Shen | Protein backbone and sidechain torsion angles predicted from NMR chemical 9 shifts using artificial neural networks[END_REF].

According to TALOS-N, the protein has 5 beta strands and 1 small helix in the N-terminal part, whereas the C-terminal part harbors a long helix (from residue 96 to 126) (Figure 2). Our NMR study of shifts of P1 will enable the investigation of its interaction with partners, in particular small RNAs. In future, determination of the structure of P1 and characterization of its dynamics will shed a new light on the three-dimensional properties of this domain and its numerous functions.

The chemical shift assignments have been deposited in the BioMagResBank (http://www.bmrb.wisc.edu) under the 27880 accession number.

Figure caption

Fig. 1 :

 1 Fig. 1: 2D 1 H-15N HSQC spectrum of 200 M sample of 15 N-labeled P1 in 100 mM NaCl, 60 mM Na 2 So 4 , 50

Fig. 2 .

 2 Fig. 2. The secondary structure propensities pSS of the P1 protein derived from TALOS-N on the basis of the chemical shifts of Hα, 15 N, Cα, Cβ and C' atoms (Shen and Bax, 2013). Positive and negative values

Acknowledgments

The CBS is a member of the French Infrastructure for Integrated Structural Biology (FRISBI), a French infrastructure supported by the National Research Agency (ANR-10-INBS-05) and is a GIS-IBIsA platform.

V. P. and F-X. G. were awarded with PhD-MESR Internships from the French Ministry of Education and Research.

Author contributions: FV and HD designed the study; VP and FXG prepared protein samples; YY and HD analyzed the data; YY, FV and H. wrote the paper.


Maxime Sauzay

Diogo Goncalves

Bertrand Sicaud

Jérôme Hazan

Pierre Lamagnere

# MATERIAUX2018-1805

Colloque, choix 1 :

Ingénierie numérique des matériaux Colloque, choix 2 :

Matériaux métalliques

Colloque, choix 3 :

Endommagement et rupture

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Votre résumé :

A température ambiante, la déformation des monocristaux et des polycristaux métalliques à structure CFC se caractérise par la formation de bandes de glissement. Ces bandes peuvent être caractérisées par de nombreuses techniques expérimentales. Elles sont observées en déformation monotone et cyclique. Leurs caractéristiques (épaisseur, glissement plastique, multiplication, microstructure) diffèrent selon le chargement et l'énergie de faute d'empilement (EFE) normalisée du fait du rôle du glissement dévié. Néanmoins, à l'échelle de la micromécanique, elles peuvent être modélisées comme des lamelles dans lesquelles se concentre le glissement plastique. Or, les modèles d'homogénéisation polycristallin, de type champs moyens (auto-cohérents) ou champs complets (EFs, FFT) ignorent cette localisation à l'échelle intra-granulaire, et donc une part de l'influence de l'EFE. Par ailleurs, ces modèles prédisent généralement l'activation très rapide de nombreux systèmes de glissement, ce qui est en contradiction avec de nombreuses observations. Ils ne reproduisent pas non le durcissement polycristallin très linéaire des matériaux à faible EFE. Enfin, même une fois introduite la plasticité non locale, ils ne prédisent pas naturellement le fort effet de l'EFE normalisée sur l'effet de taille de grain et la constante de Hall-Petch. Enfin, Un modèle d'homogénéisation polycristallin basé sur les hypothèses suivantes a donc été proposé et implémenté : i) chaque bande de glissement, caractérisée par une longueur (la taille de grain) et une épaisseur qui est mesurée expérimentalement et donc dépend de l'EFE est noyée dans une matrice élastique. Les contraintes de cisaillements sont transmis aux ligaments élastiques inter-bandes du fait du faible rapport espacement / taille de grains ; ii) chaque bande obéit à des lois de plasticité basée sur la dynamique des dislocations et la taille de grain intervient une seconde fois via la tailles des boucles de dislocations et le terme de production par « bowing-out » ; iii)

La distribution de la plasticité en cours de chargement s'effectue respectivement par multiplication des bandes ou augmentation du glissement plastique dans un nombre constant de bandes, en accord avec les observations sur les matériaux à forte et faible EFE. Les simulations prédisent des courbes de traction polycristalline en accord avec les courbes mesurées sur matériaux planaires (Cu30%Zn et acier 316L), avec un durcissement linéaire jusqu'à quelques dizaines de %. Le durcissement "concave" des métaux à forte EFE est aussi reproduit. Le nombre de systèmes activé est beaucoup plus faible et dépend de l'EFE et de la taille de grains. Enfin, la dépendance prédite de la constante de Hall-Petch vis-à-vis de l'EFE normalisée est en accord avec de nombreuses données expérimentales.

  Mots clés : Glissement, Homogénéisation, métal, Plasticité cristalline, polycristaux Conflits d'intérêts : None Declared