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The promises of vaccines based on virus-like particles stimulate demand for universal non-infectious virus-like platforms that can be efficiently grafted with large antigens. Here we harnessed the modularity and extreme affinity of the decoration protein pb10 for the capsid of bacteriophage T5. SPR experiments demonstrated that pb10 fused to mCherry or to the model antigen ovalbumin (Ova) retained picomolar affinity for DNA-free T5 capsid-like particles (T5-CLPs), while cryo-EM studies attested to the full occupancy of the 120 capsid binding sites. Mice immunisation with CLP-bound pb10-Ova chimeras elicited strong long-lasting anti-Ova humoral responses involving a large panel of isotypes, as well as CD8+T cell responses, without any extrinsic adjuvant. Therefore, T5-CLP constitutes the first DNA-free bacteriophage capsid able to irreversibly display a regular array of large antigens through highly efficient chemical-free anchoring. Its ability to elicit robust immune responses paves the way for further development of this novel vaccination platform.

Viruses can affect all life forms, raising concerns about virus detection and quantification of small nanoparticles. In this paper we use a label-free, full-field, incoherently illuminated common path interferometric method to detect, track, and quantify biotic nanoparticles. The detection consists of amplifying the light scattered by single nanoparticles in the sample solution. Then, the use of single-particle tracking analysis is used to monitor the change in particle diffusive mobility. With this approach, the recognition signature of T5 phages with purified antibodies targeting the major capsid protein is detected in a few minutes. We also tracked the interaction between SPP1 phages and physiological non-purified serum-containing multiples antibodies molecules. The first interactions occur after around one minute, and the recognition signature is detectable after minutes. In addition, we have been able to differentiate two populations of similar size of empty and full (encapsulating DNA) capsids of T5 in a heterogeneous solution demonstrating the robustness of this label-free detection approach. Furthermore, by combining the diffusion coefficient to the number of tracked particles, we were able to estimate the affinity of the virus-antibodies reaction.

(Bio-)nanoparticle analysis employing a nano-electrospray gas-phase electrophoretic mobility molecular analyzer (native nES GEMMA) also known as nES differential mobility analyzer (nES DMA) is based on surface-dry analyte separation at ambient pressure. Based on electrophoretic principles, single-charged nanoparticles are separated according to their electrophoretic mobility diameter (EMD) corresponding to the particle size for spherical analytes. Subsequently, it is possible to correlate the (bio-)nanoparticle EMDs to their molecular weight (MW) yielding a corresponding fitted curve for an investigated analyte class. Based on such a correlation, (bio-)nanoparticle MW determination via its EMD within one analyte class is possible. Turning our attention to icosahedral, non-enveloped virus-like particles (VLPs), proteinaceous shells, we set up an EMD/MW correlation. We employed native electrospray ionization mass spectrometry (native ESI MS) to obtain MW values of investigated analytes, where possible, after extensive purification. We experienced difficulties in native ESI MS with time-of-flight (ToF) detection to determine MW due to sample inherent characteristics, which was not the case for charge detection (CDMS). nES GEMMA exceeds CDMS in speed of analysis and is likewise less dependent on sample purity and homogeneity. Hence, gas-phase electrophoresis yields calculated MW values in good approximation even when charge resolution was not obtained in native ESI ToF MS. Therefore, both methods-native nES GEMMA-based MW determination via an analyte class inherent EMD/MW correlation and native ESI MS-in the end relate (bio-)nanoparticle MW values. However, they differ significantly in, e.g., ease of instrument operation, sample and analyte handling, or costs of instrumentation. Graphical abstract Electronic supplementary material The online version of this article (10.1007/s00216-019-01998-6) contains supplementary material, which is available to authorized users.

This article deals with some of the theoretical and methodological problems that arise when working with a bilingual comparable (i.e., non-parallel) journalistic corpus of financial news that is relatively large (9 million words). The corpus under study comprises two sets of texts drawn from Canadian French and English newspapers in the years between the Tech Wreck of 2001 and the financial crisis of 2007−2008. Following Davier (2015) who advocates for a broadened definition of news translation that includes intralingual activity, the authors make a case for the study of intralingual translation, or rewording, which is a fundamental feature of financial news, as journalists work to popularize specialized knowledge for lay audiences. The methodological challenges of surveying interlingual translation in a sizeable corpus of financial news are discussed in relation with the production of news in Canada. A pilot study using the lexical item “subprime” and its French equivalents illustrates how interlingual a...

Despite new transparency regulation in 2002, a lack of transparency was identified only five years later among the causes of the financial crisis in North America. With this paradox in mind, the au...

This very short text recounts my experience of translating Henri Meschonnic's essays, which combine the trials of poetry and the tribulations of texts in the humanities. I explain the reasons why I chose to translate Éthique et politique du traduire (2007) and touch on the relation between reading habits and the perception of fluency.

International audience; Bacteriophages have a prominent place in the living world. They participate to our understanding of the living world through three main aspects : (i) the dissection of the most intimist aspects of viral infection molecular mechanisms (molecular biology), (ii) the description and functioning mechanisms of ecosystems (ecology), and (iii) the adaptive dynamics of integrated viral and host-cell populations (evolution). This review looks back at the genesis of these fundamental findings and draws a picture of the most active fields of current research.; Les bactériophages tiennent une place prépondérante dans le monde vivant. Du point de vue épistémologique, ils participent à la compréhension du vivant via trois aspects fondamentaux : (i) les mécanismes moléculaires les plus intimes du fonctionnement des infections virales et de celui des cellules elles-mêmes (biologie moléculaire) ; (ii) le fonctionnement des écosystèmes (écologie) ; et (iii) la dynamique adaptative des populations virales et bactériennes (évolution). À travers une présentation historique de la découverte des bactériophages et de leurs fascinantes propriétés, cette revue relate la genèse des découvertes fondamentales associées à l’étude des bactériophages et présente une vision synthétique des champs de recherche actuels.

Dans la couverture médiatique de la crise des prêts hypothécaires à risque (dits subprimes) qui a éclaté en août 2007, la traduction s’est trouvée mobilisée du fait que les déclencheurs de cette crise étaient d’origine américaine et ont dû être expliqués par les journalistes canadiens aux lectorats anglophones et francophones. Pour présenter avec une économie de moyens des concepts compliqués et souligner la gravité de la situation, les journalistes ont recouru aux métaphores de l’accident, du cataclysme, de la catastrophe et de l’épidémie. Après analyse des métaphores conceptuelles trouvées dans La Presse, Le Devoir, The Toronto Star et The Globe and Mail, l’article démontre que, loin d’être banales, elles confortent une idéologie néolibérale de l’économie., In the media coverage of the subprime crisis of August 2007, it is through translation that journalists worked to explain its causes, which were of American origin, to the Canadian French and English readerships. In order to efficiently convey complicated concepts and the gravity of the situation, journalists resorted to metaphors of the accident, the cataclysm, the catastrophe and the epidemy. The article analyzes the conceptual metaphors found in La Presse, Le Devoir, The Toronto Star and The Globe and Mail and argues that far from being harmless commonplaces they propagate a neoliberal ideology of economics.

International audience; The first Very Large Scale Integration process with variable shape beam lithography for optomechanical devices is presented. State of the art performance was obtained with silicon microdisk resonators showing 1 million optical quality factors and 10 -17 m.Hz (-1/2) displacement resolution. Single-particle mass spectrometry could be performed with these optomechanical resonators in vacuum. The devices retained high performance when directly immersed in liquid media, allowing for biosensing experiments. These results open the door to large, dense arrays of optomechanical sensors.

Bridging the mass gap Viruses and many large biomolecule complexes are in a mass range that is challenging to measure with conventional mass spectrometry methods. Nanomechanical resonators can determine masses of impacting molecules, but separation methods often lose too much of the sample to be efficient. Dominguez-Medina et al. used an aerodynamic lens that improved separation and focusing of nebulized molecules with increasing mass. The mass of both filled and empty viral capsids was determined with an array of 20 nanoresonators. Science , this issue p. 918

Conference Report The third meeting of the French Phage Network (Phages-sur-Yvette) was supported by I2BC, CNRS (INEE and INSB institutes), INRA, University Paris-Sud, and Orsay Faculty of Sciences.; International audience; In its third year of existence, the French Phage Network (Phages.fr) is pursuing its expansion. With more than 25 groups, mostly based in France, working on the various aspects of phage research, the network has increased its visibility, interactivity, and activity. The third meeting of the Phages.fr network, held on November 2017 at the Gif-sur-Yvette Centre National de la Recherche Scientifique (CNRS) campus, was a great opportunity for many young scientists to present their work and interact with more senior scientists, amongst which several were invited from abroad. Here we provide a summary of the work presented at this occasion during the oral presentations and poster sessions.

Scientific Reports 7: Article number: 41662; published online: 06 February 2017; updated: 28 April 2017 This Article contains typographical errors. In the results section under subheading ‘The C-terminal domain adopts an immunoglobulin fold in solution’, “A search for structurally similar proteins possessing using the Dali server identified many proteins containing an Ig-like fold, including immunoglobulin receptors, fibroblast growth factor receptors and the T-cell surface glycoprotein CD4.

Capsids of double-stranded DNA (dsDNA) bacteriophages initially assemble into compact procapsids, which undergo expansion upon the genome packaging. This shell remodeling results from a structural rearrangement of head protein subunits. It is a critical step in the capsid maturation pathway that yields final particles capable to withstand the huge internal pressure generated by the packed DNA. Here, we report on the expansion process of the large capsid ( T = 13) of bacteriophage T5. We purified the intermediate prohead II form, which is competent for packaging the 121-kbp dsDNA genome, and we investigated its morphology and dimensions using cryo-electron microscopy and small-angle X-ray scattering. Decreasing the pH or the ionic strength triggers expansion of prohead II, converting them into thinner and more faceted capsids isomorphous to the mature virion particles. At low pH, prohead II expansion is a highly cooperative process lacking any detectable intermediate. This two-state reorganization of the capsid lattice per se leads to a remarkable stabilization of the particle. The melting temperature of expanded T5 capsid is virtually identical with that of more complex shells that are reinforced by inter-subunit cross-linking (HK97) or by additional cementing proteins (T4). The T5 capsid with its “simple” two-state conversion thus appears to be a very attractive model for investigating the mechanism of the large-scale allosteric transition that takes place upon the genome packaging of dsDNA bacteriophages.

The self assembly of the icosahedral capsid of double-stranded DNA (dsDNA) viruses is a highly regulated unidirectional process that proceeds by steps, starting with the association of the full-length capsid protein subunits into a precursor capsid form. Several maturation steps follow (proteolytic cleavage, conformational reorganization of capsid subunits, and stabilization processes) that take place before, during, or after the packaging of the viral genome (34). Finally, the mature capsid has to withstand the high internal pressure imposed by the densely packed genome as well as environmental stresses after exit from the bacterial host. Capsid assembly thus relies on highly regulated protein-protein interactions that transition from the dynamic association and maturation phases to the stable and robust endpoint. The architectural principles that govern icosahedral capsids comprising several hundred identical protein subunits were formulated by Caspar and Klug (2), who introduced the concept of quasi-equivalence. Accordingly, capsid proteins have enough flexibility in shape and binding interfaces to assemble into hexamers (hexons) or pentamers (pentons) and to form hexon-penton and hexon-hexon contacts that are nearly equivalent to each other. In addition, assembly is tightly controlled to yield a single size in most cases, with the precise geometry of the capsid being described by the lattice triangulation number T. Viruses have developed various strategies to control the proper assembly of their capsid. The T4 bacteriophage (26) and human adenoviruses (14), for example, use distinct proteins to form hexons and pentons, while others, including herpesviruses and phage λ, use the same protein. Capsid assembly may rely on scaffolding proteins that subsequently are expelled from the capsid during maturation and DNA encapsidation (6, 15). If the scaffolding protein is mutated or absent, incorrect structures are formed, which can be open tubes (T4) or smaller particles (P22, φ29, herpesvirus) (1, 3, 10, 27, 28, 35). Capsid assembly also may rely only on the major head protein, as shown in the case of the lambdoid coliphage HK97 (T=7). Its major head protein, gp5, contains a mature domain and a 102-residue amino-terminal Δ domain that is cleaved after initial assembly by a viral protease and thus is considered to play the role of the scaffolding protein in other phages (5, 7). Furthermore, in vitro and in vivo studies have shown that preformed pentamers and hexamers of uncleaved gp5 accurately assemble into T=7 icosahedral shells without the requirement of the portal protein (5, 7, 9, 36). Gp5 thus carries by itself all the information needed to assemble into procapsids. The Siphoviridae coliphage T5 differs from other members of this family, like phage λ or HK97, by the large size of its dsDNA genome, 121,750 bp (GenBank accession numbers {"type":"entrez-nucleotide","attrs":{"text":"AY587007","term_id":"59897142","term_text":"AY587007"}}AY587007, {"type":"entrez-nucleotide","attrs":{"text":"AY692264","term_id":"51511954","term_text":"AY692264"}}AY692264, and {"type":"entrez-nucleotide","attrs":{"text":"AY543070","term_id":"45774915","term_text":"AY543070"}}AY543070). Similarly to HK97, the T5 genome does not encode a scaffolding protein. The structure of the T5 icosahedral mature capsid was solved by cryoelectron microscopy (cryo-EM) and image reconstruction revealing the first capsid of a wild-type single-layered virus to have the triangulation number T=13 (11) (Fig. ​(Fig.1).1). The 90-nm-diameter capsid shell consists of the major head protein pb8 (39), whose subunits form 11 pentons located at the vertices and 120 hexons located at the faces. The hexons are decorated by an accessory protein, pb10 (11, 32). The 12th vertex is occupied by the connector, which comprises a dodecamer ring of the portal protein pb7. pb8 is a 50-kDa protein with two domains in its full-length form (called pb8p). pb8p undergoes proteolytic cleavage during morphogenesis, leaving a 32-kDa mature protein (pb8m) in the viral particle (38). N-terminal sequencing indicated that the severed region of pb8m corresponds to the 159 aminoterminal residues (11). This N-terminal extension, called the Δ domain by analogy with the HK97 major head protein, is predicted to have a high α-helical content mostly organized as a coiled-coil formation, and it may function as a scaffold domain (11). The mechanism by which the Δ domain is cleaved is unknown but likely involves pb11, a head maturation protease identified on the genome and located upstream of the gene encoding pb8 (GenBank accession number {"type":"entrez-nucleotide","attrs":{"text":"AY692264","term_id":"51511954","term_text":"AY692264"}}AY692264). A schematic of the T5 head assembly pathway is presented in Fig. ​Fig.1.1. Compared to that of HK97, the T5 capsid exhibits a higher level of complexity. Several constraints must be fulfilled to assemble its T=13 shell. A unique protein must associate into pentons occupying the vertices and into two kinds of hexons, one interacting both with pentons and hexons and the other exclusively with hexons. This raises the question of whether a T=13 procapsid can be assembled in vitro with the unique contribution of the major head protein carrying both structural and scaffold functions. To address these questions, we have expressed and purified pb8 and searched for physicochemical conditions allowing its assembly. We demonstrate that the precursor form of pb8 with its Δ domain (pb8p) assembles in vitro into diverse structures, including expanded and contracted tubes, and that the conformational flexibility introduced in pb8p by Ca2+ allows it to assemble into procapsids with internal radial structures corresponding to the Δ domain. FIG. 1. Bacteriophage T5 head assembly and characteristics of pb8 constructs. (A) Schematic of the head assembly pathway. The precursor form of the major head protein, pb8p, includes a scaffolding Δ domain (residues 1 to 159; represented as a white triangle) ...

L’être humain est produit par le langage davantage qu’il ne le produit. Lorsque ce constat psychanalytique est posé sur le terrain de la traductologie, celle-ci est amenée à envisager des sujets habituellement considérés comme étant hors de son champ de compétence, tels que les lapsus. Dans le sillage des travaux de François Peraldi, nous montrons les affinités épistémologiques et conceptuelles de la psychanalyse et de la traduction et, plus encore, la nécessité pour la traduction d’incorporer certains vecteurs de réflexion psychanalytiques. Dans cette visée, nous relançons l’injonction que Peraldi a faite aux traducteurs et qui rejoint la poétique du traduire d’Henri Meschonnic : se mettre à l’écoute du corps de la parole et de la parole du corps dans le langage. Cette écoute doit passer par une sensibilisation du corps traduisant, par l’éveil de sa fonction érotique, qui se trouve à l’état latent., Humans are produced by language rather than produce it. When this psychoanalytical contention is brought to translation theory, it pushes the latter to consider objects usually deemed out of its conceptual reach, such as slips of the pen. In the wake of François Peraldi, we stress the epistemological and conceptual affinities that psychoanalysis and translation share, but more so the necessity for translation to integrate certain psychoanalytical viewpoints. Like Peraldi we urge translators to give ear to the body of the word and the word of the body, a stance which also builds on Henri Meschonnic’s poetics of translation. The ability to listen is only possible if the body translating becomes sensitized, if its erotic function is aroused from its latent state.

S’inscrivant dans le cadre plus large des enjeux lies a la traduction du genre grammatical, l’article propose une etude ponctuelle sur la traduction de l’adjectif possessif de la troisieme personne, his/her, dans la narration de recits erotiques. Puisque le possessif en francais n’indique pas le genre du possesseur, comment traduire his et her, si courts et efficaces, tout en evitant l’equivoque de son/sa et la lourdeur de la resonance pronominale a lui/a elle ? L’observation d’un corpus erotique anglais et francais a revele diverses strategies d’ecriture servant a propulser le debit narratif dans le but de tenir le lecteur en haleine et le titiller.

In this study, an MS-based proteomics approach to characterizing the virion structural proteins of the novel marine 'photosynthetic' phage S-PM2 is presented. The virus infects ecologically important cyanobacteria of the genus Synechococcus that make a substantial contribution to primary production in the oceans. The S-PM2 genome encodes 236 ORFs, some of which exhibit similarity to known phage virion structural proteins, but the majority (54%) show no detectable homology to known proteins from other organisms. Using public and in-house bioinformatics; tools the proteome of S-PM2 was predicted and a database compatible with MS-based search engines was constructed. S-PM2 virion proteins were resolved by SIDS-PAGE, excised, tryptically digested and analysed by LC-ESI-MS/MS. The resulting MS data were searched against the database. A parallel control study was undertaken on the well-characterized coliphage T4 in order to assess the sensitivity and efficiency of this approach. In total, 11 of the 15 S-PM2 proteins, predicted to be virion proteins by bioinformatics approaches, were confirmed as such, together with the identification of a further 12 novel structural proteins. In the case of T4, 24 of the 39 known virion structural proteins were identified, including the major tail-fibre proteins. This approach has wide-ranging applicability and can be applied to any novel organism whose genome encodes ORFs with few detectable homologies in the public databases.

The 90-nm-diameter capsid of coliphage T5 is organized with T=13 icosahedral geometry and encloses a double-stranded DNA genome that measures 121kbp. Its assembly follows a path similar to that of phage HK97 but yielding a larger structure that includes 775 subunits of the major head protein, 12 subunits of the portal protein and 120 subunits of the decoration protein. As for phage HK97, T5 encodes the scaffold function as an N-terminal extension (∆-domain) to the major head protein that is cleaved by the maturation protease after assembly of the initial prohead I form and prior to DNA packaging and capsid expansion. Although the major head protein alone is sufficient to assemble capsid-like particles, the yield is poor and includes many deformed structures. Here we explore the role of both the portal and the protease in capsid assembly by generating constructs that include the major head protein and a combination of protease (wild type or an inactive mutant) and portal proteins and overexpressing them in Escherichia coli. Our results show that the inactive protease mutant acts to trigger assembly of the major head protein, probably through binding to the ∆-domain, while the portal protein regulates assembly into the correct T=13 geometry. A cryo-electron microscopy reconstruction of prohead I including inactivated protease reveals density projecting from the prohead interior surface toward its center that is compatible with the ∆-domain, as well as additional internal density that we assign as the inactivated protease. These results reveal complexity in T5 beyond that of the HK97 system.

Evolutionary relationships between viruses may be obscure by protein sequence but unmasked by structure. Analysis of bacteriophage T5 by cryo-electron microscopy and protein sequence analysis reveals analogies with HK97 and T4 that suggest a mosaic of such connections. The T5 capsid is consistent with the HK97 capsid protein fold but has a different geometry, incorporating three additional hexamers on each icosahedral facet. Similarly to HK97, the T5 major capsid protein has an N-terminal extension, or Delta-domain that is missing in the mature capsid, and by analogy with HK97, may function as an assembly or scaffold domain. This Delta-domain is predicted to be largely coiled-coil, as for that of HK97, but is approximately 70% longer correlating with the larger capsid. Thus, capsid architecture appears likely to be specified by the Delta-domain. Unlike HK97, the T5 capsid binds a decoration protein in the center of each hexamer similarly to the "hoc" protein of phage T4, suggesting a common role for these molecules. The tail-tube has unusual trimeric symmetry that may aid in the unique two-stage DNA-ejection process, and joins the tail-tip at a disk where tail fibers attach. This intriguing mix of characteristics embodied by phage T5 offers insights into virus assembly, subunit function, and the evolutionary connections between related viruses.

Les affinités sont étonnantes entre les constatations épistémologiques que la théorie du chaos a amené les sciences dites exactes à faire et une pensée de la traduction libérée d’une conception fixiste du sens. Penser la traduction en passant par la théorie du chaos, c’est surtout annuler les dichotomies inopérantes échues des conceptualisations traditionnelles, visée participant des discours de la « troisième voie ». Non-linéarité, sensibilité critique aux conditions initiales et géométrie fractale sont autant de thèmes qui potentialisent la théorisation de la traduction dans une épistémologie tablant sur la mouvance et la subjectivité des paramètres d’interprétation, sur l’instabilité persistante entre l’ordre et le désordre, sur la valeur heuristique donc positive du désordre et sur l’incomplétude., The affinities that exist between the epistemological observations of the so-called “exact” sciences arrived at via the chaos theory, on the one hand, and the notion of translation as being free of a fixist conception of meaning, on the other hand, are remarkable indeed. To consider translation in light of the chaos theory is above all to do away with the ineffective dichotomies stemming from traditional conceptualizations, an aim partaking of the discourse of the “third path.” Nonlinearity, critical sensitivity to initial conditions, fractal geometry – these are just so many themes potentializing the theorization of translation into an epistemology based on the ever-changing, subjective nature of the parameters of interpretation, on the state of persistent instability between order and disorder, on the heuristic and therefore positive value of disorder, and on incompleteness.

Bacteriophage terminases are essential molecular motors involved in the encapsidation of viral DNA. They are hetero-multimers whose large subunit encodes both ATPase and endonuclease activities. Although the ATPase domain is well characterized from sequence and functional analysis, the C-terminal region remains poorly defined. We describe sequence-structure comparisons of the endonuclease region of various bacteriophages that revealed new sequence similarities shared by this region and the Holliday junction resolvase RuvC and to a lesser extent the HIV integrase and the ribonuclease H. Extensive sequence comparison and motif refinement led to a common signature of terminases and resolvases with three conserved acidic residues engaged in catalytic activity. Sequence analyses were validated by in vivo and in vitro functional assays showing that the nuclease activity of the endonuclease domain of bacteriophage T5 terminase was abolished by mutation of any of the three predicted catalytic aspartates. Overall, these data suggest that the endonuclease domains of terminases operate autonomously and that they adopt a fold similar to that of resolvases and share the same divalent cation-dependent enzymatic mechanism.

International audience; The role of the outer-membrane iron transporter FhuA as a potential receptor for the antimicrobial peptide MccJ25 (microcin J25) was studied through a series of in vivo and in vitro experiments. The requirement for both FhuA and the inner-membrane TonB-ExbB-ExbD complex was demonstrated by antibacterial assays using complementation of an fhuA(-) strain and by using isogenic strains mutated in genes encoding the protein complex respectively. In addition, MccJ25 was shown to block phage T5 infection of Escherichia coli, in vivo, by inhibiting phage adhesion, which suggested that MccJ25 prevents the interaction between the phage and its receptor FhuA. This in vivo activity was confirmed in vitro, as MccJ25 inhibited phage T5 DNA ejection triggered by purified FhuA. Direct interaction of MccJ25 with FhuA was demonstrated for the first time by size-exclusion chromatography and isothermal titration calorimetry. MccJ25 bound to FhuA with a 2:1 stoichiometry and a K(d) of 1.2 microM. Taken together, our results demonstrate that FhuA is the receptor for MccJ25 and that the ligand-receptor interaction may occur in the absence of other components of the bacterial membrane. Finally, both differential scanning calorimetry and antimicrobial assays showed that MccJ25 binding involves external loops of FhuA. Unlike native MccJ25, a thermolysin-cleaved MccJ25 variant was unable to bind to FhuA and failed to prevent phage T5 infection of E. coli. Therefore the Val11-Pro16 beta-hairpin region of MccJ25, which is disrupted upon cleavage by thermolysin, is required for microcin recognition.

We discuss current models of phage DNA transport through membranes. We present results that attempt to answer the following questions: is there a single mechanism of transport for all types of phage? is DNA transported as a free molecule or in association with proteins? what is the driving force for transport?

FhuA (MM 78.9 kDa) is an Escherichia coli outer membrane protein that transports iron coupled to ferrichrome and is the receptor for a number of bacteriophages and protein antibiotics. Its three-dimensional structure consists of a 22-stranded beta-barrel lodged in the membrane, extracellular hydrophilic loops, and a globular domain (the "cork") located within the beta-barrel and occluding it. This unexpected structure raises questions about the connectivity of the different domains and their respective roles in the different functions of the protein. To address these questions, we have compared the properties of the wild-type receptor to those of a mutated FhuA (FhuA Delta) missing a large part of the cork. Differential scanning calorimetry experiments on wild-type FhuA indicated that the cork and the beta-barrel behave as autonomous domains that unfold at 65 and 75 degrees C, respectively. Ferrichrome had a strong stabilizing effect on the loops and cork since it shifted the first transition to 71.4 degrees C. Removal of the cork destabilized the protein since a unique transition at 61.6 degrees C was observed even in the presence of ferrichrome. FhuA Delta showed an increased sensitivity to proteolysis and to denaturant agents and an impairment in phage T5 and ferrichrome binding.

Bacteriophage T5 represents a large family of lytic Siphoviridae infecting Gram-negative bacteria. The low-resolution structure of T5 showed the T=13 geometry of the capsid and the unusual trimeric organization of the tail tube, and the assembly pathway of the capsid was established. Although major structural proteins of T5 have been identified in these studies, most of the genes encoding the morphogenesis proteins remained to be identified. Here, we combine a proteomic analysis of T5 particles with a bioinformatic study and electron microscopic immunolocalization to assign function to the genes encoding the structural proteins, the packaging proteins, and other nonstructural components required for T5 assembly. A head maturation protease that likely accounts for the cleavage of the different capsid proteins is identified. Two other proteins involved in capsid maturation add originality to the T5 capsid assembly mechanism: the single head-to-tail joining protein, which closes the T5 capsid after DNA packaging, and the nicking endonuclease responsible for the single-strand interruptions in the T5 genome. We localize most of the tail proteins that were hitherto uncharacterized and provide a detailed description of the tail tip composition. Our findings highlight novel variations of viral assembly strategies and of virion particle architecture. They further recommend T5 for exploring phage structure and assembly and for deciphering conformational rearrangements that accompany DNA transfer from the capsid to the host cytoplasm.

Lorsqu’Henri Meschonnic a publie son essai Ethique et politique du traduire en 2007, nous travaillions sur la question de savoir pourquoi ses travaux n’etaient pas passes par la filiere d’importation par laquelle les ecrits de nombreux penseurs francais avaient ete traduits et recus sous l’etiquette americaine de la French Theory (Jacques Derrida, Roland Barthes, Michel Foucault, Gilles Deleuze, Julia Kristeva, etc.). Au lieu d’approfondir cette question, dont les reponses n’auraient en rien ...

Tails of bacteriophage T5 (a member of the Siphoviridae family) were studied by electron microscopy. For the distal parts of the L-shaped tail fibres, which are involved in host cell receptor binding, a low-resolution volume was calculated. Several C-terminal fragments of the fibre were expressed and purified. Crystals of two of them were obtained that belonged to space groups P63 and R32 and diffracted synchrotron radiation to 2.3 and 2.9 A resolution, respectively. A single-wavelength anomalous dispersion data set to 2.5 A resolution was also collected from a selenomethionine-derivatized crystal of one of the fragments, which belonged to space group C2.

International audience; Within tailed bacteriophages, interaction of the receptor-binding protein (RBP) with the target cell triggers viral DNA ejection into the host cytoplasm. In the case of phage T5, the RBP pb5 and the receptor FhuA, an outer membrane protein of Escherichia coli, have been identified. Here, we use small angle neutron scattering and electron microscopy to investigate the FhuA-pb5 complex. Specific deuteration of one of the partners allows the complete masking in small angle neutron scattering of the surfactant and unlabeled proteins when the complex is solubilized in the fluorinated surfactant F6-DigluM. Thus, individual structures within a membrane protein complex can be described. The solution structure of FhuA agrees with its crystal structure; that of pb5 shows an elongated shape. Neither displays significant conformational changes upon interaction. The mechanism of signal transduction within phage T5 thus appears different from that of phages binding cell wall saccharides, for which structural information is available.

A filamentous phage-displayed random hexapeptide library was screened on the adenovirus type 2 (Ad2) penton capsomer and its separate domains, penton base, full-length fiber, fiber shaft and fiber knob. Affinity supports were designed to immobilize the penton ligate with a preferred orientation, via immuno-adsorption to pre-coated antibody. Three classes of phagotopes were distinguished in the eluates from the penton and fiber domains. (i) The first class represented peptide sequences identified in certain Ad2 capsid proteins, protein IIIa, protein pVIII, penton base and penton fiber. Data from specific ligand elution of phages bound to fiber and penton base wild-types and mutants suggested that the region overlapping the RLSNLLG motif at residues 254-260 in the penton base and the FNPVYP motif at residues 11-16 in the fiber tail formed mutual interacting sites in the penton capsomer. (ii) The second class consisted of phagotopes homologous to peptide sequences found in host cell membrane proteins involved in receptor or adhesion functions. One of the most abundant species corresponded to a conserved motif present in the beta-strand B of type III modules of human fibronectin. In addition, phages which were screened for their failure to bind to penton base RGD mutants were found to carry consensus motifs to peptide sequences present in the RGD recognition site of human integrin beta subunits. (iii) The third class comprised peptide motifs common to both viral and cellular proteins, suggesting that a mechanism of ligand exchange could occur during virus entry and uncoating, and virus assembly and release.

International audience; The majority of bacterial viruses are bacteriophages bearing a tail that serves to recognise the bacterial surface and deliver the genome into the host cell. Infection is initiated by the irreversible interaction between the viral receptor binding protein (RBP) and a receptor at the surface of the bacterium. This interaction results ultimately in the phage DNA release in the host cytoplasm. Phage T5 infects Escher-ichia coli after binding of its RBP pb5 to the outer membrane ferrichrome transporter FhuA. Here, we have studied the complex formed by pb5 and FhuA by a variety of biophysical and biochemical techniques. We show that unlike RBPs of known structures, pb5 probably folds as a unique domain fulfilling both functions of binding to the host receptor and interaction with the rest of the phage. Pb5 likely binds to the domain occluding the b-barrel of FhuA as well as to external loops of the barrel. Furthermore, upon binding to FhuA, pb5 undergoes conformational changes, at the secondary and tertiary structure level that would be the key to the transmission of the signal through the tail to the capsid, triggering DNA release. This is the first structural information regarding the binding of a RBP to a proteic receptor. Ó 2012 Elsevier Masson SAS. All rights reserved.

Phage T5 injects its DNA into Escherichia coli cells in two steps; 8% of the chromosome is first injected, and then there is a pause during which proteins encoded by this DNA fragment are synthesized allowing the remaining DNA to be injected. Using a potassium-selective electrode, we show that the injection of the two DNA fragments is associated with an efflux in two steps, of cytoplasmic potassium. The rate of efflux is linearly related to the number of added phages suggesting that each phage induces the formation of at least one channel in the inner membrane. The first efflux occurs even in depolarized cells suggesting that the insertion and the opening of the channel can take place in the absence of the electrochemical gradient of protons (delta mu H+). The channel is in a closed configuration during the time required for the synthesis of the phage-encoded proteins; this closing and the second efflux are prevented by the depolarization of the cell. The insertion of the channel in the inner membrane requires a fluid membrane. The results obtained suggest that the function of this channel is to translocate phage T5 DNA.

L’érotique du traduire envisage la volupté, ou le vif plaisir des sens, et l’attirance du corps traduisant pour les attributs du corps textuel au nombre des motifs de la traduction. Il s’agit d’élargir la conceptualisation de la traduction comme processus essentiellement idéel et d’investir le corps traduisant de ses facultés sensibles. Tributaire de la caresse levinassienne, l’érotique du traduire écarte le rapport unilatéral du sujet-traducteur à l’objet-texte et inscrit la traduction dans l’interrelation des corps. Également moteur de subversion, l’érotique veut sortir la traduction de la finalité, de la rationalité et de la culpabilité., In an erotics of translation, sensual pleasure and physical attraction of the translating body for the textual body are considered among the motives behind translation. The representation of translation as an essentially ideal process needs to be broadened in order to grant the translating body full use of her senses and sensibility. Akin to Levinas’ caress, an erotics of translation dismisses the oneway relationship between the translator-as-subject and the text-as-object, arguing in favour of a bilateral relationship. Subversive as well, an erotics of translation wants to pull translation away from final cause, rationality and guilt.

Concentration and purification of infectious particles are prerequisites for structural and functional characterization of bacteriophages. The methods detailed in the first part of this chapter outline the protocols commonly used to obtain purified phages: the concentration of phage particles by precipitation with polyethylene glycol and their purification by centrifugation in CsCl step gradients and subsequently by equilibrium centrifugation. This sequence of procedures, if carried out as a whole, ensures a purification of high quality, which is well suited for most analytical techniques used to characterize bacteriophage particles. The second part of this chapter describes the preparation of "ghosts" or DNA-less bacteriophages. These particles should be preferred to the entire bacteriophages for one-dimensional SDS-PAGE analysis of phage structural proteins, since running of the phage proteins through the gel is not disturbed by the presence of the phage DNA. This allows an optimal resolution, which is necessary for proteomic approaches such as N-terminal protein sequencing or mass spectrometry using proteins isolated from distinct gel bands.

Concentration and purification of infectious particles are prerequisites for structural and functional characterization of bacteriophages. The methods detailed in the first part of this chapter outline the protocols commonly used to obtain purified phages: the concentration of phage particles by precipitation with polyethylene glycol and their purification by centrifugation in CsCl step gradients and subsequently by equilibrium centrifugation. This sequence of procedures, if carried out as a whole, ensures a purification of high quality, which is well suited for most analytical techniques used to characterize bacteriophage particles. The second part of this chapter describes the preparation of "ghosts" or DNA-less bacteriophages. These particles should be preferred to the entire bacteriophages for one-dimensional SDS-PAGE analysis of phage structural proteins, since running of the phage proteins through the gel is not disturbed by the presence of the phage DNA. This allows an optimal resolution, which is necessary for proteomic approaches such as N-terminal protein sequencing or mass spectrometry using proteins isolated from distinct gel bands.

We report a bioinformatic and functional characterization of Pb2, a 121-kDa multimeric protein that forms phage T5 straight fiber and is implicated in DNA transfer into the host. Pb2 was predicted to consist of three domains. Region I (residues 1-1030) was mainly organized in coiled coil and shared features of tape measure proteins. Region II (residues 1030-1076) contained two alpha-helical transmembrane segments. Region III (residues 1135-1148) included a metallopeptidase motif. A truncated version of Pb2 (Pb2-Cterm, residues 964-1148) was expressed and purified. Pb2-Cterm shared common features with fusogenic membrane polypeptides. It formed oligomeric structures and inserted into liposomes triggering their fusion. Pb2-Cterm caused beta-galactosidase release from Escherichia coli cells and in vitro peptidoglycan hydrolysis. Based on these multifunctional properties, we propose that binding of phage T5 to its receptor triggers large conformational changes in Pb2. The coiled coil region would serve as a sensor for triggering the opening of the head-tail connector. The C-terminal region would gain access to the host envelope, permitting the local degradation of the peptidoglycan and the formation of the DNA pore by fusion of the two membranes.