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Accueil > Publications

Publications Département B3S

2018


  • N. Abdollahi, A. Albani, E. Anthony, A. Baud, M. Cardon, R. Clerc, D. Czernecki, R. Conte, L. David, A. Delaune, S. Djerroud, P. Fourgoux, N. Guiglielmoni, J. Laurentie, N. Lehmann, C. Lochard, R. Montagne, V. Myrodia, V. Opuu, E. Parey, L. Polit, S. Privé, C. Quignot, M. Ruiz-Cuevas, M. Sissoko, N. Sompairac, A. Vallerix, V. Verrecchia, M. Delarue, R. Guérois, Y. Ponty, S. Sacquin-Mora, A. Carbone, C. Froidevaux, S. Le Crom, O. Lespinet, M. Weigt, S. Abboud, J. Bernardes, G. Bouvier, C. Dequeker, A. Ferré, P. Fuchs, G. Lelandais, P. Poulain, H. Richard, H. Schweke, E. Laine, et A. Lopes, « Meet-U: Educating through research immersion », PLoS computational biology, vol. 14, nᵒ 3, p. e1005992, mars 2018.
    Résumé : We present a new educational initiative called Meet-U that aims to train students for collaborative work in computational biology and to bridge the gap between education and research. Meet-U mimics the setup of collaborative research projects and takes advantage of the most popular tools for collaborative work and of cloud computing. Students are grouped in teams of 4-5 people and have to realize a project from A to Z that answers a challenging question in biology. Meet-U promotes "coopetition," as the students collaborate within and across the teams and are also in competition with each other to develop the best final product. Meet-U fosters interactions between different actors of education and research through the organization of a meeting day, open to everyone, where the students present their work to a jury of researchers and jury members give research seminars. This very unique combination of education and research is strongly motivating for the students and provides a formidable opportunity for a scientific community to unite and increase its visibility. We report on our experience with Meet-U in two French universities with master's students in bioinformatics and modeling, with protein-protein docking as the subject of the course. Meet-U is easy to implement and can be straightforwardly transferred to other fields and/or universities. All the information and data are available at www.meet-u.org.
    Mots-clés : AMIG, B3S, BDG, BIM.


  • C. Adam, R. Guérois, A. Citarella, L. Verardi, F. Adolphe, C. Béneut, V. Sommermeyer, C. Ramus, J. Govin, Y. Couté, et V. Borde, « The PHD finger protein Spp1 has distinct functions in the Set1 and the meiotic DSB formation complexes », PLOS Genetics, vol. 14, nᵒ 2, p. e1007223, févr. 2018.

  • L. Ahmad, S. Plancqueel, V. Dubosclard, N. Lazar, W. Ghattas, I. Li de la Sierra-Gallay, H. van Tilbeurgh, et L. Salmon, « Crystal structure of phosphomannose isomerase from Candida albicans complexed with 5-phospho-d-arabinonhydrazide », FEBS letters, avr. 2018.
    Résumé : Type I phosphomannose isomerases (PMIs) are zinc-dependent monofunctional metalloenzymes catalysing the reversible isomerization of d-mannose 6-phosphate to d-fructose 6-phosphate. 5-Phospho-d-arabinonhydrazide (5PAHz), designed as an analogue of the enediolate high-energy intermediate, strongly inhibits PMI from Candida albicans (CaPMI). In this study, we report the 3D crystal structure of CaPMI complexed with 5PAHz at 1.85 Å resolution. The high-resolution structure suggests that Glu294 is the catalytic base that transfers a proton between the C1 and C2 carbon atoms of the substrate. Bidentate coordination of the inhibitor explains the stereochemistry of the isomerase activity, as well as the absence of both anomerase and C2-epimerase activities for Type I PMIs. A detailed mechanism of the reversible isomerization is proposed.
    Mots-clés : B3S, Candida albicans, enzyme mechanism, FAAM, inhibitor, phosphomannose isomerase, zinc metalloenzyme.

  • G. Annio, T. Jennings, O. Tagit, et N. Hildebrandt, « Sensitivity-Enhancement of FRET Immunoassays by Multiple-Antibody Conjugation on Quantum Dots », Bioconjugate Chemistry, mai 2018.
    Résumé : Quantum dots (QDs) are not only advantageous for color-tuning, improved brightness, and high stability, but their nanoparticle surfaces also allow for the attachment of many biomolecules. Because IgG antibodies (ABs) are in the same size range of biocompatible QDs and the AB orientation after conjugation to the QD is often random, it is difficult to predict if few or many ABs per QD will lead to an efficient AB-QD conjugate. This is particularly true for homogeneous Förster resonance energy transfer (FRET) sandwich immunoassays, for which the ABs on the QD must bind a biomarker that needs to bind a second AB-FRET-conjugate. Here, we investigate the performance of Tb-to-QD FRET immunoassays against total prostate specific antigen (TPSA) by changing the number of ABs per QD while leaving all the other assay components unchanged. We first characterize the AB-QD conjugation by various spectroscopic, microscopic, and chromatographic techniques and then quantify the TPSA immunoassay performance regarding sensitivity, limit of detection, and dynamic range. Our results show that an increasing conjugation ratio leads to significantly enhanced FRET immunoassays. These findings will be highly important for developing QD-based immunoassays in which the concentrations of both ABs and QDs can significantly influence the assay performance.
    Mots-clés : B3S, NANO.

  • A. Barwinska-Sendra, A. Baslé, K. J. Waldron, et S. Un, « A charge polarization model for the metal-specific activity of superoxide dismutases », Physical chemistry chemical physics: PCCP, janv. 2018.
    Résumé : The pathogenicity of Staphylococcus aureus is enhanced by having two superoxide dismutases (SODs): a Mn-specific SOD and another that can use either Mn or Fe. Using 94 GHz electron-nuclear double resonance (ENDOR) and electron double resonance detected (ELDOR)-NMR we show that, despite their different metal-specificities, their structural and electronic similarities extend down to their active-site 1H- and 14N-Mn(ii) hyperfine interactions. However these interactions, and hence the positions of these nuclei, are different in the inactive Mn-reconstituted Escherichia coli Fe-specific SOD. Density functional theory modelling attributes this to a different angular position of the E. coli H171 ligand. This likely disrupts the Mn-H171-E170' triad causing a shift in charge and in metal redox potential, leading to the loss of activity. This is supported by the correlated differences in the Mn(ii) zero-field interactions of the three SOD types and suggests that the triad is important for determining metal specific activity.
    Mots-clés : B3S, BHFMR.

  • A. Berto, J. Yu, S. Morchoisne-Bolhy, C. Bertipaglia, R. Vallee, J. Dumont, F. Ochsenbein, R. Guerois, et V. Doye, « Disentangling the molecular determinants for Cenp-F localization to nuclear pores and kinetochores », EMBO reports, vol. 19, nᵒ 5, mai 2018.
    Résumé : Cenp-F is a multifaceted protein implicated in cancer and developmental pathologies. The Cenp-F C-terminal region contains overlapping binding sites for numerous proteins that contribute to its functions throughout the cell cycle. Here, we focus on the nuclear pore protein Nup133 that interacts with Cenp-F both at nuclear pores in prophase and at kinetochores in mitosis, and on the kinase Bub1, known to contribute to Cenp-F targeting to kinetochores. By combining in silico structural modeling and yeast two-hybrid assays, we generate an interaction model between a conserved helix within the Nup133 β-propeller and a short leucine zipper-containing dimeric segment of Cenp-F. We thereby create mutants affecting the Nup133/Cenp-F interface and show that they prevent Cenp-F localization to the nuclear envelope, but not to kinetochores. Conversely, a point mutation within an adjacent leucine zipper affecting the kinetochore targeting of Cenp-F KT-core domain impairs its interaction with Bub1, but not with Nup133, identifying Bub1 as the direct KT-core binding partner of Cenp-F. Finally, we show that Cenp-E redundantly contributes together with Bub1 to the recruitment of Cenp-F to kinetochores.
    Mots-clés : AMIG, B3S, Cenp‐F, in silico modeling, kinetochores, mitosin, nuclear pore.

  • A. Boussac, I. Ugur, A. Marion, M. Sugiura, V. R. I. Kaila, et A. W. Rutherford, « The low spin - high spin equilibrium in the S2-state of the water oxidizing enzyme », Biochimica Et Biophysica Acta, vol. 1859, nᵒ 5, p. 342-356, févr. 2018.
    Résumé : In Photosystem II (PSII), the Mn4CaO5-cluster of the active site advances through five sequential oxidation states (S0to S4) before water is oxidized and O2is generated. Here, we have studied the transition between the low spin (LS) and high spin (HS) configurations of S2using EPR spectroscopy, quantum chemical calculations using Density Functional Theory (DFT), and time-resolved UV-visible absorption spectroscopy. The EPR experiments show that the equilibrium between S2LSand S2HSis pH dependent, with a pKa ≈ 8.3 (n ≈ 4) for the native Mn4CaO5and pKa ≈ 7.5 (n ≈ 1) for Mn4SrO5. The DFT results suggest that exchanging Ca with Sr modifies the electronic structure of several titratable groups within the active site, including groups that are not direct ligands to Ca/Sr, e.g., W1/W2, Asp61, His332 and His337. This is consistent with the complex modification of the pKaupon the Ca/Sr exchange. EPR also showed that NH3addition reversed the effect of high pH, NH3-S2LSbeing present at all pH values studied. Absorption spectroscopy indicates that NH3is no longer bound in the S3TyrZstate, consistent with EPR data showing minor or no NH3-induced modification of S3and S0. In both Ca-PSII and Sr-PSII, S2HSwas capable of advancing to S3at low temperature (198 K). This is an experimental demonstration that the S2LSis formed first and advances to S3via the S2HSstate without detectable intermediates. We discuss the nature of the changes occurring in the S2LSto S2HStransition which allow the S2HSto S3transition to occur below 200 K. This work also provides a protocol for generating S3in concentrated samples without the need for saturating flashes.
    Mots-clés : B3S, DFT, EPR, Mn(4)CaO(5) cluster, Oxygen evolution, Photosystem II, PS2, Spin state.

  • M. Byrdin, C. Duan, D. Bourgeois, et K. Brettel, « A Long-Lived Triplet State Is the Entrance Gateway to Oxidative Photochemistry in Green Fluorescent Proteins », Journal of the American Chemical Society, vol. 140, nᵒ 8, p. 2897-2905, févr. 2018.
    Résumé : Though ubiquitously used as selective fluorescence markers in cellular biology, fluorescent proteins (FPs) still have not disclosed all of their surprising properties. One important issue, notably for single-molecule applications, is the nature of the triplet state, suggested to be the starting point for many possible photochemical reactions leading to phenomena such as blinking or bleaching. Here, we applied transient absorption spectroscopy to characterize dark states in the prototypical enhanced green fluorescent protein (EGFP) of hydrozoan origin and, for comparison, in IrisFP, a representative phototransformable FP of anthozoan origin. We identified a long-lived (approximately 5 ms) dark state that is formed with a quantum yield of approximately 1% and has pronounced absorption throughout the visible-NIR range (peak at around 900 nm). Detection of phosphorescence emission with identical kinetics and excitation spectrum allowed unambiguous identification of this state as the first excited triplet state of the deprotonated chromophore. This triplet state was further characterized by determining its phosphorescence emission spectrum, the temperature dependence of its decay kinetics and its reactivity toward oxygen and electron acceptors and donors. It is suggested that it is this triplet state that lies at the origin of oxidative photochemistry in green FPs, leading to phenomena such as so-called "oxidative redding", "primed photoconversion", or, in a manner similar to that previously observed for organic dyes, redox induced blinking control with the reducing and oxidizing system ("ROXS").
    Mots-clés : B3S, LPB.


  • M. Cardoso Dos Santos, J. Goetz, H. Bartenlian, K. - L. Wong, L. J. Charbonnière, et N. Hildebrandt, « Autofluorescence-Free Live-Cell Imaging Using Terbium Nanoparticles », Bioconjugate Chemistry, févr. 2018.

  • F. Celli, A. Petitalot, C. Samson, F. - X. Theillet, et S. Zinn-Justin, « 1 H,13C and15N backbone resonance assignment of the lamin C-terminal region specific to prelamin A », Biomolecular NMR assignments, mars 2018.
    Résumé : Lamins are the main components of the nucleoskeleton. They form a protein meshwork that underlies the inner nuclear membrane. Mutations in the LMNA gene coding for A-type lamins (lamins A and C) cause a large panel of human diseases, referred to as laminopathies. These diseases include muscular dystrophies, lipodystrophies and premature aging diseases. Lamin A exhibits a C-terminal region that is different from lamin C and is post-translationally modified. It is produced as prelamin A and it is then farnesylated, cleaved, carboxymethylated and cleaved again in order to become mature lamin A. In patients with the severe Hutchinson-Gilford progeria syndrome, a specific single point mutation in LMNA leads to an aberrant splicing of the LMNA gene preventing the post-translational processing of prelamin A. This leads to the accumulation of a permanently farnesylated lamin A mutant lacking 50 amino acids named progerin. We here report the NMR1H,15N,13CO,13Cα and13Cβ chemical shift assignment of the C-terminal region that is specific to prelamin A, from amino acid 567 to amino acid 664. We also report the NMR1H,15N,13CO,13Cα and13Cβ chemical shift assignment of the C-terminal region of the progerin variant, from amino acid 567 to amino acid 614. Analysis of these chemical shift data confirms that both prelamin A and progerin C-terminal domains are largely disordered and identifies a common partially populated α-helix from amino acid 576 to amino acid 585. This helix is well conserved from fishes to mammals.
    Mots-clés : B3S, INTGEN, Intrinsically disordered protein, NMR spectroscopy, Nuclear envelope, Nucleoskeleton.

  • H. - J. Chang, P. Mayonove, A. Zavala, A. De Visch, P. Minard, M. Cohen-Gonsaud, et J. Bonnet, « A Modular Receptor Platform To Expand the Sensing Repertoire of Bacteria », ACS synthetic biology, vol. 7, nᵒ 1, p. 166-175, janv. 2018.
    Résumé : Engineered bacteria promise to revolutionize diagnostics and therapeutics, yet many applications are precluded by the limited number of detectable signals. Here we present a general framework to engineer synthetic receptors enabling bacterial cells to respond to novel ligands. These receptors are activated via ligand-induced dimerization of a single-domain antibody fused to monomeric DNA-binding domains (split-DBDs). Using E. coli as a model system, we engineer both transmembrane and cytosolic receptors using a VHH for ligand detection and demonstrate the scalability of our platform by using the DBDs of two different transcriptional regulators. We provide a method to optimize receptor behavior by finely tuning protein expression levels and optimizing interdomain linker regions. Finally, we show that these receptors can be connected to downstream synthetic gene circuits for further signal processing. The general nature of the split-DBD principle and the versatility of antibody-based detection should support the deployment of these receptors into various hosts to detect ligands for which no receptor is found in nature.
    Mots-clés : B3S, MIP.

  • G. Chararalambidis, S. Das, A. Trapali, A. Quaranta, M. Orio, Z. Halime, P. Fertey, R. Guillot, A. Coutsolelos, W. Leibl, A. Aukauloo, et M. Sircoglou, « Water Molecules Gating a Photoinduced One Electron Two Protons Transfer in a Tyr/His model of Photosystem II », Angewandte Chemie (International Ed. in English), mai 2018.
    Résumé : In this report, we investigate on a biomimetic model of a H-bonded TyrZ/His190 pair covalently attached to a porphyrin sensitizer. Laser flash photolysis in presence of an external electron acceptor reveals the need of water molecules to unlock the light-induced oxidation of the phenol through an intramolecular pathway. Kinetics monitoring encompasses two fast phases with distinct spectral properties. The first phase is related to one-electron transfer from the phenol to the porphyrin radical cation coupled with a domino two-proton transfer leading to the ejection of a proton from the imidazole-phenol pair. The second phase concerns the convoy of the released proton to the porphyrin N4 coordinating cavity. Importantly, our study provides an unprecedented example of light induced electron transfer process in a TyrZ/His190 model of Photosystem II, evidencing the movement of both the phenol and imidazole protons along an isoenergetic pathway.
    Mots-clés : artificial photosynthesis, B3S, LPB, Proton Coupled Electron Transfer, TyrZ-His190 model.

  • J. - H. Chen, L. - J. Yu, A. Boussac, Z. - Y. Wang-Otomo, T. Kuang, et J. - R. Shen, « Properties and structure of a low-potential, penta-heme cytochrome c 552 from a thermophilic purple sulfur photosynthetic bacterium Thermochromatium tepidum », Photosynthesis Research, avr. 2018.
    Résumé : The thermophilic purple sulfur bacterium Thermochromatium tepidum possesses four main water-soluble redox proteins involved in the electron transfer behavior. Crystal structures have been reported for three of them: a high potential iron-sulfur protein, cytochrome c', and one of two low-potential cytochrome c 552 (which is a flavocytochrome c) have been determined. In this study, we purified another low-potential cytochrome c 552 (LPC), determined its N-terminal amino acid sequence and the whole gene sequence, characterized it with absorption and electron paramagnetic spectroscopy, and solved its high-resolution crystal structure. This novel cytochrome was found to contain five c-type hemes. The overall fold of LPC consists of two distinct domains, one is the five heme-containing domain and the other one is an Ig-like domain. This provides a representative example for the structures of multiheme cytochromes containing an odd number of hemes, although the structures of multiheme cytochromes with an even number of hemes are frequently seen in the PDB database. Comparison of the sequence and structure of LPC with other proteins in the databases revealed several characteristic features which may be important for its functioning. Based on the results obtained, we discuss the possible intracellular function of this LPC in Tch. tepidum.
    Mots-clés : B3S, Crystal structure, Cytochrome c, Electron transfer, Multiheme, PS2, Purple sulfur bacteria, Thermochromatium tepidum.

  • M. David, C. Lebrun, T. Duguet, F. Talmont, R. Beech, S. Orlowski, F. André, R. K. Prichard, et A. Lespine, « Structural model, functional modulation by ivermectin and tissue localization of Haemonchus contortus P-glycoprotein-13 », International Journal for Parasitology. Drugs and Drug Resistance, vol. 8, nᵒ 1, p. 145-157, avr. 2018.
    Résumé : Haemonchus contortus, one of the most economically important parasites of small ruminants, has become resistant to the anthelmintic ivermectin. Deciphering the role of P-glycoproteins in ivermectin resistance is desirable for understanding and overcoming this resistance. In the model nematode, Caenorhabditis elegans, P-glycoprotein-13 is expressed in the amphids, important neuronal structures for ivermectin activity. We have focused on its ortholog in the parasite, Hco-Pgp-13. A 3D model of Hco-Pgp-13, presenting an open inward-facing conformation, has been constructed by homology with the Cel-Pgp-1 crystal structure. In silico docking calculations predicted high affinity binding of ivermectin and actinomycin D to the inner chamber of the protein. Following in vitro expression, we showed that ivermectin and actinomycin D modulated Hco-Pgp-13 ATPase activity with high affinity. Finally, we found in vivo Hco-Pgp-13 localization in epithelial, pharyngeal and neuronal tissues. Taken together, these data suggest a role for Hco-Pgp-13 in ivermectin transport, which could contribute to anthelmintic resistance.
    Mots-clés : ABC transporters, B3S, Haemonchus contortus, Homology modeling, Ivermectin, LPSM, LSOD, Nematode, P-glycoprotein.


  • A. De Muyt, A. Pyatnitskaya, J. Andréani, L. Ranjha, C. Ramus, R. Laureau, A. Fernandez-Vega, D. Holoch, E. Girard, J. Govin, R. Margueron, Y. Couté, P. Cejka, R. Guérois, et V. Borde, « A meiotic XPF–ERCC1-like complex recognizes joint molecule recombination intermediates to promote crossover formation », Genes & Development, vol. 32, nᵒ 3-4, p. 283-296, févr. 2018.


  • Z. Edoo, L. Iannazzo, F. Compain, I. Li de la Sierra Gallay, H. van Tilbeurgh, M. Fonvielle, F. Bouchet, E. Le Run, J. - L. Mainardi, M. Arthur, M. Ethève-Quelquejeu, et J. - E. Hugonnet, « Synthesis of avibactam derivatives and activity on β-lactamases and peptidoglycan biosynthesis enzymes of mycobacteria », Chemistry - A European Journal, mars 2018.


  • J. B. Fernandes, M. Duhamel, M. Seguéla-Arnaud, N. Froger, C. Girard, S. Choinard, V. Solier, N. De Winne, G. De Jaeger, K. Gevaert, P. Andrey, M. Grelon, R. Guerois, R. Kumar, et R. Mercier, « FIGL1 and its novel partner FLIP form a conserved complex that regulates homologous recombination », PLOS Genetics, vol. 14, nᵒ 4, p. e1007317, avr. 2018.

  • M. - H. Ha-Thi, V. - T. Pham, T. Pino, V. Maslova, A. Quaranta, C. Lefumeux, W. Leibl, et A. Aukauloo, « Photoinduced electron transfer in a molecular dyad by nanosecond pump-pump-probe spectroscopy », Photochemical & Photobiological Sciences: Official Journal of the European Photochemistry Association and the European Society for Photobiology, juin 2018.
    Résumé : The design of robust and inexpensive molecular photocatalysts for the conversion of abundant stable molecules like H2O and CO2 into an energetic carrier is one of the major fundamental questions for scientists nowadays. The outstanding challenge is to couple single photoinduced charge separation events with the sequential accumulation of redox equivalents at the catalytic unit for performing multielectronic catalytic reactions. Herein, double excitation by nanosecond pump-pump-probe experiments was used to interrogate the photoinduced charge transfer and charge accumulation on a molecular dyad composed of a porphyrin chromophore and a ruthenium-based catalyst in the presence of a reversible electron acceptor. An accumulative charge transfer state is unattainable because of rapid reverse electron transfer to the photosensitizer upon the second excitation and the low driving force of the forward photodriven electron transfer reaction. Such a method allows the fundamental understanding of the relaxation mechanism after two sequential photon absorptions, deciphering the undesired electron transfer reactions that limit the charge accumulation efficiency. This study is a step toward the improvement of synthetic strategies of molecular photocatalysts for light-induced charge accumulation and more generally, for solar energy conversion.
    Mots-clés : B3S, LPB.

  • G. Hutinet, A. Besle, O. Son, S. McGovern, R. Guerois, M. - A. Petit, F. Ochsenbein, et F. Lecointe, « Sak4 of Phage HK620 Is a RecA Remote Homolog With Single-Strand Annealing Activity Stimulated by Its Cognate SSB Protein », Frontiers in Microbiology, vol. 9, p. 743, 2018.
    Résumé : Bacteriophages are remarkable for the wide diversity of proteins they encode to perform DNA replication and homologous recombination. Looking back at these ancestral forms of life may help understanding how similar proteins work in more sophisticated organisms. For instance, the Sak4 family is composed of proteins similar to the archaeal RadB protein, a Rad51 paralog. We have previously shown that Sak4 allowed single-strand annealing in vivo, but only weakly compared to the phage λ Redβ protein, highlighting putatively that Sak4 requires partners to be efficient. Here, we report that the purified Sak4 of phage HK620 infecting Escherichia coli is a poorly efficient annealase on its own. A distant homolog of SSB, which gene is usually next to the sak4 gene in various species of phages, highly stimulates its recombineering activity in vivo. In vitro, Sak4 binds single-stranded DNA and performs single-strand annealing in an ATP-dependent way. Remarkably, the single-strand annealing activity of Sak4 is stimulated by its cognate SSB. The last six C-terminal amino acids of this SSB are essential for the binding of Sak4 to SSB-covered single-stranded DNA, as well as for the stimulation of its annealase activity. Finally, expression of sak4 and ssb from HK620 can promote low-level of recombination in vivo, though Sak4 and its SSB are unable to promote strand exchange in vitro. Regarding its homology with RecA, Sak4 could represent a link between two previously distinct types of recombinases, i.e., annealases that help strand exchange proteins and strand exchange proteins themselves.
    Mots-clés : AMIG, annealase, B3S, bacteriophage, Rad51 paralog, RecA, recombineering, Sak4, SSB, strand exchange protein.

  • S. M. Kapetanaki, M. J. Burton, J. Basran, C. Uragami, P. C. E. Moody, J. S. Mitcheson, R. Schmid, N. W. Davies, P. Dorlet, M. H. Vos, N. M. Storey, et E. Raven, « A mechanism for CO regulation of ion channels », Nature Communications, vol. 9, nᵒ 1, p. 907, 2018.
    Résumé : Despite being highly toxic, carbon monoxide (CO) is also an essential intracellular signalling molecule. The mechanisms of CO-dependent cell signalling are poorly defined, but are likely to involve interactions with heme proteins. One such role for CO is in ion channel regulation. Here, we examine the interaction of CO with KATP channels. We find that CO activates KATP channels and that heme binding to a CXXHX16H motif on the SUR2A receptor is required for the CO-dependent increase in channel activity. Spectroscopic and kinetic data were used to quantify the interaction of CO with the ferrous heme-SUR2A complex. The results are significant because they directly connect CO-dependent regulation to a heme-binding event on the channel. We use this information to present molecular-level insight into the dynamic processes that control the interactions of CO with a heme-regulated channel protein, and we present a structural framework for understanding the complex interplay between heme and CO in ion channel regulation.
    Mots-clés : B3S, LSOD.


  • H. Kubota-Kawai, R. Mutoh, K. Shinmura, P. Sétif, M. M. Nowaczyk, M. Rögner, T. Ikegami, H. Tanaka, et G. Kurisu, « X-ray structure of an asymmetrical trimeric ferredoxin–photosystem I complex », Nature Plants, vol. 4, nᵒ 4, p. 218-224, 2018.

  • F. Lallemand, A. Petitalot, S. Vacher, L. de Koning, K. Taouis, B. S. Lopez, S. Zinn-Justin, N. Dalla-Venezia, W. Chemlali, A. Schnitzler, R. Lidereau, I. Bieche, et S. M. Caputo, « Involvement of the FOXO6 transcriptional factor in breast carcinogenesis », Oncotarget, vol. 9, nᵒ 7, p. 7464-7475, janv. 2018.
    Résumé : In mammals, FOXO transcriptional factors form a family of four members (FOXO1, 3, 4, and 6) involved in the modulation proliferation, apoptosis, and carcinogenesis. The role of the FOXO family in breast cancer remains poorly elucidated. According to the cellular context and the stage of the disease, FOXOs can have opposite effects on carcinogenesis. To study the role of FOXOs in breast carcinogenesis in more detail, we examined their expression in normal tissues, breast cell lines, and a large series of breast tumours of human origin. We found a very low physiological level ofFOXO6expression in normal adult tissues and high levels of expression in foetal brain.FOXOgene expressions fluctuate specifically in breast cancer cells compared to normal cells, suggesting that these genes may have different roles in breast carcinogenesis. For the first time, we have shown that, among the variousFOXOgenes, onlyFOXO6was frequently highly overexpressed in breast cell lines and tumours. We also found that inhibition of the endogenous expression of FOXO6 by a specific siRNA inhibited the growth of the human breast cell lines MDA-MB-468 and HCC-38. FACS and Western blot analysis showed that inhibition of endogenous expression of FOXO6 induced accumulation of cells in G0/G1 phase of the cell cycle, but not apoptosis. These results tend to demonstrate that the overexpression of the humanFOXO6gene that we highlighted in the breast tumors stimulates breast carcinogenesis by activating breast cancer cell proliferation.
    Mots-clés : B3S, cervical squamous cell carcinoma, endometrial adenocarcinoma, gynecological cancers, INTGEN, prognosis, uc.189.


  • L. Lecoq, S. Wang, T. Wiegand, S. Bressanelli, M. Nassal, B. H. Meier, et A. Böckmann, « Localizing conformational hinges by NMR: where do HBV core proteins adapt for capsid assembly? », ChemPhysChem, mars 2018.

  • L. Lecoq, S. Wang, T. Wiegand, S. Bressanelli, M. Nassal, B. H. Meier, et A. Böckmann, « Solid-state [13C-15N] NMR resonance assignment of hepatitis B virus core protein », Biomolecular NMR assignments, vol. 12, nᵒ 1, p. 205-214, avr. 2018.
    Résumé : Each year, nearly 900,000 deaths are due to serious liver diseases caused by chronic hepatitis B virus infection. The viral particle is composed of an outer envelope and an inner icosahedral nucleocapsid formed by multiple dimers of a ~ 20 kDa self-assembling core protein (Cp). Here we report the solid-state 13C and 15N resonance assignments of the assembly domain, Cp149, of the core protein in its capsid form. A secondary chemical shift analysis of the 140 visible residues suggests an overall alpha-helical three-dimensional fold matching that derived for Cp149 from the X-ray crystallography of the capsid, and from solution-state NMR of the Cp149 dimer. Interestingly, however, at three distinct regions the chemical shifts in solution differ significantly between core proteins in the capsid state versus in the dimer state, strongly suggesting the respective residues to be involved in capsid assembly.
    Mots-clés : AMIG, Assignments, B3S, Core protein, Hepatitis B virus, IMAPP, Nucleocapsid, Solid-state NMR.


  • M. J. Llansola-Portoles, K. Redeckas, S. Streckaité, C. Ilioaia, A. A. Pascal, A. Telfer, M. Vengris, L. Valkunas, et B. Robert, « Lycopene crystalloids exhibit singlet exciton fission in tomatoes », Physical Chemistry Chemical Physics, vol. 20, nᵒ 13, p. 8640-8646, 2018.

  • L. Marichal, J. - P. Renault, S. Chédin, G. Lagniel, G. Klein, J. - C. Aude, C. Tellier-Lebegue, J. Armengaud, S. Pin, J. Labarre, et Y. Boulard, « Importance of Post-translational Modifications in the Interaction of Proteins with Mineral Surfaces: The Case of Arginine Methylation and Silica surfaces », Langmuir: the ACS journal of surfaces and colloids, vol. 34, nᵒ 18, p. 5312-5322, mai 2018.
    Résumé : Understanding the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest for both basic research and practical applications involving nanotechnology. From the list of cellular proteins with the highest affinity for silica nanoparticles, we highlighted the group of proteins containing arginine-glycine-glycine (RGG) motifs. Biochemical experiments confirmed that RGG motifs interact strongly with the silica surfaces. The affinity of these motifs is further increased when the R residue is asymmetrically, but not symmetrically, dimethylated. Molecular dynamics simulations show that the asymmetrical dimethylation generates an electrostatic asymmetry in the guanidinium group of the R residue, orientating and stabilizing it on the silica surface. The RGG motifs (methylated or not) systematically target the siloxide groups on the silica surface through an ionic interaction, immediately strengthened by hydrogen bonds with proximal silanol and siloxane groups. Given that, in vivo, RGG motifs are often asymmetrically dimethylated by specific cellular methylases, our data add support to the idea that this type of methylation is a key mechanism for cells to regulate the interaction of the RGG proteins with their cellular partners.
    Mots-clés : B3S, BDG, BIM, IMAPP, PEPS.


  • A. A. Nadaradjane, R. Guerois, et J. Andreani, « Protein-Protein Docking Using Evolutionary Information », in Protein Complex Assembly, vol. 1764, J. A. Marsh, Éd. New York, NY: Springer New York, 2018, p. 429-447.

  • M. Messant, S. Timm, A. Fantuzzi, W. Weckwerth, H. Bauwe, B. Rutherford, et A. Krieger-Liszkay, « Glycolate induces redox tuning of photosystem II in vivo: study of a photorespiration mutant », Plant Physiology, mai 2018.
    Résumé : Bicarbonate removal from the non-heme iron at the acceptor side of photosystem II (PSII) was recently shown to shift the midpoint potential of the primary quinone acceptor QA to a more positive potential and lowers the yield of singlet oxygen (1O2) production. The presence of QA- results in weaker binding of bicarbonate, suggesting a redox-based regulatory and protective mechanism where loss of bicarbonate or exchange of bicarbonate by other small carboxylic acids may protect PSII against 1O2 in vivo under photorespiratory conditions. Here we compared the properties of QA in the Arabidopsis (Arabidopsis thaliana) photorespiration mutant hpr1-1, deficient in NADH-dependent, peroxisomal hydroxypyruvate reductase 1 (HPR1), which accumulates glycolate in leaves, to the wild type. Photosynthetic electron transport was affected in the mutant, and chlorophyll fluorescence showed slower electron transport between QA and QB in the mutant. Glycolate induced an increase in the temperature maximum of thermoluminescence emission indicating a shift of the midpoint potential of QA to a more positive value. The yield of 1O2 production was lowered in thylakoid membranes isolated from hpr1-1 compared to the wild type, consistent with a higher potential of QA/QA-. In addition, electron donation to photosystem I was affected in hpr1-1 at higher light intensities consistent with diminished electron transfer out of photosystem II. This study indicates that replacement of bicarbonate at the non-heme iron by a small carboxylate anion occurs in plants in vivo. These findings suggested that replacement of the bicarbonate on the non-heme iron by glycolate may represent a regulatory mechanism that protects PSII against photo-oxidative stress under low CO2 conditions.
    Mots-clés : B3S, MROP.


  • T. Meyer, S. Renoud, A. Vigouroux, A. Miomandre, V. Gaillard, I. Kerzaon, C. Prigent-Combaret, G. Comte, S. Moréra, L. Vial, et C. Lavire, « Regulation of hydroxycinnamic acid degradation drives Agrobacterium fabrum lifestyles. », Molecular Plant-Microbe Interactions, févr. 2018.

  • T. Meyer, A. Vigouroux, M. Aumont-Niçaise, G. Comte, L. Vial, C. Lavire, et S. Morera, « The plant defense signal galactinol is specifically used as a nutrient by the bacterial pathogen Agrobacterium fabrum », The Journal of Biological Chemistry, mars 2018.
    Résumé : The bacterial plant pathogen Agrobacterium fabrum uses periplasmic binding proteins (PBPs) along with ABC transporters to import a wide variety of plant molecules as nutrients. Nonetheless, how A. fabrum acquires plant metabolites is incompletely understood. Using genetic approaches and affinity measurements, we identified here the PBP MelB and its transporter as being responsible for the uptake of the raffinose family of oligosaccharides (RFOs), which are the most widespread Dgalactose containing oligosaccharides in higher plants. We also found that the RFO precursor galactinol, recently described as a plant defense molecule, is imported into Agrobacterium via MelB with nanomolar range affinity. Structural analyses and binding mode comparisons of the X-ray structures of MelB in complex with raffinose, stachyose, galactinol, galactose and melibiose (a raffinose degradation product) revealed how MelB recognizes the nonreducing end galactose common to all these ligands and that MelB has a strong preference for a two-unit sugar ligand. Of note, MelB conferred a competitive advantage to A. fabrum in colonizing the rhizosphere of tomato plants. Our integrative work highlights the structural and functional characteristics of melibiose and galactinol assimilation by A. fabrum, leading to a competitive advantage for these bacteria in the rhizosphere. We propose that the PBP MelB, which is highly conserved among both symbionts and pathogens from Rhizobiace family, is a major trait in these bacteria required for early steps of plant colonization.
    Mots-clés : ABC transporter, agrobacterium, B3S, bacteria, crystal structure, galactinol, MESB3S, microbiology, periplasmic binding protein, PF, PIM, RFOs, sugar transport.

  • S. Missoury, S. Plancqueel, I. Li de la Sierra-Gallay, W. Zhang, D. Liger, D. Durand, R. Dammak, B. Collinet, et H. van Tilbeurgh, « The structure of the TsaB/TsaD/TsaE complex reveals an unexpected mechanism for the bacterial t6A tRNA-modification », Nucleic Acids Research, mai 2018.
    Résumé : The universal N6-threonylcarbamoyladenosine (t6A) modification at position A37 of ANN-decoding tRNAs is essential for translational fidelity. In bacteria the TsaC enzyme first synthesizes an l-threonylcarbamoyladenylate (TC-AMP) intermediate. In cooperation with TsaB and TsaE, TsaD then transfers the l-threonylcarbamoyl-moiety from TC-AMP onto tRNA. We determined the crystal structure of the TsaB-TsaE-TsaD (TsaBDE) complex of Thermotoga maritima in presence of a non-hydrolysable AMPCPP. TsaE is positioned at the entrance of the active site pocket of TsaD, contacting both the TsaB and TsaD subunits and prohibiting simultaneous tRNA binding. AMPCPP occupies the ATP binding site of TsaE and is sandwiched between TsaE and TsaD. Unexpectedly, the binding of TsaE partially denatures the active site of TsaD causing loss of its essential metal binding sites. TsaE interferes in a pre- or post-catalytic step and its binding to TsaBD is regulated by ATP hydrolysis. This novel binding mode and activation mechanism of TsaE offers good opportunities for antimicrobial drug development.
    Mots-clés : B3S, FAAM.


  • P. Müller, E. Ignatz, S. Kiontke, K. Brettel, et L. - O. Essen, « Sub-nanosecond tryptophan radical deprotonation mediated by a protein-bound water cluster in class II DNA photolyases », Chemical Science, vol. 9, nᵒ 5, p. 1200-1212, 2018.

  • M. Nakamura, A. Boussac, et M. Sugiura, « Consequences of structural modifications in cytochrome b559 on the electron acceptor side of Photosystem II », Photosynthesis Research, mai 2018.
    Résumé : Cytb559 in Photosystem II is a heterodimeric b-type cytochrome. The subunits, PsbE and PsbF, consist each in a membrane α-helix. Mutants were previously designed and studied in Thermosynechococcus elongatus (Sugiura et al., Biochim Biophys Acta 1847:276-285, 2015) either in which an axial histidine ligand of the haem-iron was substituted for a methionine, the PsbE/H23M mutant in which the haem was lacking, or in which the haem environment was modified, the PsbE/Y19F and PsbE/T26P mutants. All these mutants remained active showing that the haem has no structural role provided that PsbE and PsbF subunits are present. Here, we have carried on the characterization of these mutants. The following results were obtained: (i) the Y19F mutation hardly affect the Em of Cytb559, whereas the T26P mutation converts the haem into a form with a Em much below 0 mV (so low that it is likely not reducible by QB-) even in an active enzyme; (ii) in the PsbE/H23M mutant, and to a less extent in PsbE/T26P mutant, the electron transfer efficiency from QA- to QB is decreased; (iii) the lower Em of the QA/QA- couple in the PsbE/H23M mutant correlates with a higher production of singlet oxygen; (iv) the superoxide and/or hydroperoxide formation was not increased in the PsbE/H23M mutant lacking the haem, whereas it was significantly larger in the PsbE/T26P. These data are discussed in view of the literature to discriminate between structural and redox roles for the haem of Cytb559 in the production of reactive oxygen species.
    Mots-clés : Acceptor side, B3S, Cytb 559, Haem axial ligand, Photosystem II, PS2, Redox.

  • T. Q. Nguyen, M. Chenon, F. Vilela, C. Velours, M. Aumont-Nicaise, J. Andreani, P. F. Varela, P. Llinas, et J. Ménétrey, « Correction: Structural plasticity of the N-terminal capping helix of the TPR domain of kinesin light chain », PloS One, vol. 13, nᵒ 5, p. e0197193, 2018.
    Résumé : [This corrects the article DOI: 10.1371/journal.pone.0186354.].
    Mots-clés : AMIG, B3S, MIKICA, PF, PIM.

  • D. P. O'Brien, A. C. S. Perez, J. Karst, S. E. Cannella, V. Y. N. Enguéné, A. Hessel, D. Raoux-Barbot, A. Voegele, O. Subrini, M. Davi, J. I. Guijarro, B. Raynal, B. Baron, P. England, B. Hernandez, M. Ghomi, V. Hourdel, C. Malosse, J. Chamot-Rooke, P. Vachette, D. Durand, S. Brier, D. Ladant, et A. Chenal, « Calcium-dependent disorder-to-order transitions are central to the secretion and folding of the CyaA toxin of Bordetella pertussis, the causative agent of whooping cough », Toxicon: Official Journal of the International Society on Toxinology, janv. 2018.
    Résumé : The adenylate cyclase toxin (CyaA) plays an essential role in the early stages of respiratory tract colonization by Bordetella pertussis, the causative agent of whooping cough. Once secreted, CyaA invades eukaryotic cells, leading to cell death. The cell intoxication process involves a unique mechanism of translocation of the CyaA catalytic domain directly across the plasma membrane of the target cell. Herein, we review our recent results describing how calcium is involved in several steps of this intoxication process. In conditions mimicking the low calcium environment of the crowded bacterial cytosol, we show that the C-terminal, calcium-binding Repeat-in-ToXin (RTX) domain of CyaA, RD, is an extended, intrinsically disordered polypeptide chain with a significant level of local, secondary structure elements, appropriately sized for transport through the narrow channel of the secretion system. Upon secretion, the high calcium concentration in the extracellular milieu induces the refolding of RD, which likely acts as a scaffold to favor the refolding of the upstream domains of the full-length protein. Due to the presence of hydrophobic regions, CyaA is prone to aggregate into multimeric forms in vitro, in the absence of a chaotropic agent. We have recently defined the experimental conditions required for CyaA folding, comprising both calcium binding and molecular confinement. These parameters are critical for CyaA folding into a stable, monomeric and functional form. The monomeric, calcium-loaded (holo) toxin exhibits efficient liposome permeabilization and hemolytic activities in vitro, even in a fully calcium-free environment. By contrast, the toxin requires sub-millimolar calcium concentrations in solution to translocate its catalytic domain across the plasma membrane, indicating that free calcium in solution is actively involved in the CyaA toxin translocation process. Overall, this data demonstrates the remarkable adaptation of bacterial RTX toxins to the diversity of calcium concentrations it is exposed to in the successive environments encountered in the course of the intoxication process.
    Mots-clés : B3S, Bordetella pertussis, Calcium, CyaA toxin, Disorder-to-order transition, FAAM, Folding, Protein secretion, Whooping cough.

  • C. Orelle, C. Durmort, K. Mathieu, B. Duchêne, S. Aros, F. Fenaille, F. André, C. Junot, T. Vernet, et J. - M. Jault, « A multidrug ABC transporter with a taste for GTP », Scientific Reports, vol. 8, nᵒ 1, p. 2309, févr. 2018.
    Résumé : During the evolution of cellular bioenergetics, many protein families have been fashioned to match the availability and replenishment in energy supply. Molecular motors and primary transporters essentially need ATP to function while proteins involved in cell signaling or translation consume GTP. ATP-Binding Cassette (ABC) transporters are one of the largest families of membrane proteins gathering several medically relevant members that are typically powered by ATP hydrolysis. Here, a Streptococcus pneumoniae ABC transporter responsible for fluoroquinolones resistance in clinical settings, PatA/PatB, is shown to challenge this concept. It clearly favors GTP as the energy supply to expel drugs. This preference is correlated to its ability to hydrolyze GTP more efficiently than ATP, as found with PatA/PatB reconstituted in proteoliposomes or nanodiscs. Importantly, the ATP and GTP concentrations are similar in S. pneumoniae supporting the physiological relevance of GTP as the energy source of this bacterial transporter.
    Mots-clés : B3S, LSOD.

  • M. Parlato, F. Charbit-Henrion, J. Pan, C. Romano, R. Duclaux-Loras, M. - H. Le Du, N. Warner, P. Francalanci, J. Bruneau, M. Bras, M. Zarhrate, B. Bègue, N. Guegan, S. Rakotobe, N. Kapel, P. De Angelis, A. M. Griffiths, K. Fiedler, E. Crowley, F. Ruemmele, A. M. Muise, et N. Cerf-Bensussan, « Human ALPI deficiency causes inflammatory bowel disease and highlights a key mechanism of gut homeostasis », EMBO molecular medicine, mars 2018.
    Résumé : Herein, we report the first identification of biallelic-inherited mutations inALPIas a Mendelian cause of inflammatory bowel disease in two unrelated patients.ALPIencodes for intestinal phosphatase alkaline, a brush border metalloenzyme that hydrolyses phosphate from the lipid A moiety of lipopolysaccharides and thereby drastically reduces Toll-like receptor 4 agonist activity. Prediction tools and structural modelling indicate that all mutations affect critical residues or inter-subunit interactions, and heterologous expression in HEK293T cells demonstrated that allALPImutations were loss of function.ALPImutations impaired either stability or catalytic activity of ALPI and rendered it unable to detoxify lipopolysaccharide-dependent signalling. Furthermore, ALPI expression was reduced in patients' biopsies, and ALPI activity was undetectable in ALPI-deficient patient's stool. Our findings highlight the crucial role of ALPI in regulating host-microbiota interactions and restraining host inflammatory responses. These results indicate thatALPImutations should be included in screening for monogenic causes of inflammatory bowel diseases and lay the groundwork for ALPI-based treatments in intestinal inflammatory disorders.
    Mots-clés : B3S, inflammatory bowel diseases, intestinal phosphatase alkaline, INTGEN, monogenic disease.

  • A. Pichard-Kostuch, W. Zhang, D. Liger, M. - C. Daugeron, J. Letoquart, I. Li de la Sierra-Gallay, P. Forterre, B. Collinet, H. van Tilbeurgh, et T. Basta, « Structure-function analysis of Sua5 protein reveals novel functional motifs required for the biosynthesis of the universal t6A tRNA modification », RNA (New York, N.Y.), avr. 2018.
    Résumé : N6-threonyl-carbamoyl adenosine (t6A) is a universal tRNA modification found at position 37, next to the anticodon, in almost all tRNAs decoding ANN codons (where N = A, U, G or C). t6A stabilizes the codon-anticodon interaction and hence promotes translation fidelity. The first step of the biosynthesis of t6A, the production of threonyl-carbamoyl adenylate (TC-AMP), is catalyzed by the Sua5/TsaC family of enzymes. While TsaC is a single domain protein, Sua5 enzymes are composed of the TsaC-like domain, a linker and an extra domain called SUA5 of unknown function. In the present study, we report structure-function analysis of Pyrococcus abyssi Sua5 (Pa-Sua5). Crystallographic data revealed binding sites for bicarbonate substrate and pyrophosphate product. The linker of Pa-Sua5 forms a loop structure that folds into the active site gorge and closes it. Using structure-guided mutational analysis we established that the conserved sequence motifs in the linker and the domain-domain interface are essential for the function of Pa-Sua5. We propose that the linker participates actively in the biosynthesis of TC-AMP by binding to ATP/PPi and by stabilizing the N-carboxy-L-threonine intermediate. Hence, TsaC orthologs which lack such a linker and SUA5 domain use different mechanism for TC-AMP synthesis.
    Mots-clés : ARCHEE, B3S, FAAM, MICROBIO, Sua5, t6A37, threonylcarbamoyl adenosine, tRNA modification, TsaC.

  • C. Quignot, J. Rey, J. Yu, P. Tufféry, R. Guerois, et J. Andreani, « InterEvDock2: an expanded server for protein docking using evolutionary and biological information from homology models and multimeric inputs », Nucleic Acids Research, mai 2018.
    Résumé : Computational protein docking is a powerful strategy to predict structures of protein-protein interactions and provides crucial insights for the functional characterization of macromolecular cross-talks. We previously developed InterEvDock, a server for ab initio protein docking based on rigid-body sampling followed by consensus scoring using physics-based and statistical potentials, including the InterEvScore function specifically developed to incorporate co-evolutionary information in docking. InterEvDock2 is a major evolution of InterEvDock which allows users to submit input sequences - not only structures - and multimeric inputs and to specify constraints for the pairwise docking process based on previous knowledge about the interaction. For this purpose, we added modules in InterEvDock2 for automatic template search and comparative modeling of the input proteins. The InterEvDock2 pipeline was benchmarked on 812 complexes for which unbound homology models of the two partners and co-evolutionary information are available in the PPI4DOCK database. InterEvDock2 identified a correct model among the top 10 consensus in 29% of these cases (compared to 15-24% for individual scoring functions) and at least one correct interface residue among 10 predicted in 91% of these cases. InterEvDock2 is thus a unique protein docking server, designed to be useful for the experimental biology community. The InterEvDock2 web interface is available at http://bioserv.rpbs.univ-paris-diderot.fr/services/InterEvDock2/.
    Mots-clés : AMIG, B3S.


  • J. A. Romero-Espinoza, Y. Moreno-Valencia, R. H. Coronel-Tellez, M. Castillejos-Lopez, A. Hernandez, A. Dominguez, A. Miliar-Garcia, A. Barbachano-Guerrero, R. Perez-Padilla, A. Alejandre-Garcia, et J. A. Vazquez-Perez, « Virome and bacteriome characterization of children with pneumonia and asthma in Mexico City during winter seasons 2014 and 2015 », PLOS ONE, vol. 13, nᵒ 2, p. e0192878, févr. 2018.

  • H. Safya, A. Mellouk, J. Legrand, S. M. Le Gall, M. Benbijja, C. Kanellopoulos-Langevin, J. M. Kanellopoulos, et P. Bobé, « Variations in Cellular Responses of Mouse T Cells to Adenosine-5'-Triphosphate Stimulation Do Not Depend on P2X7 Receptor Expression Levels but on Their Activation and Differentiation Stage », Frontiers in Immunology, vol. 9, p. 360, 2018.
    Résumé : A previous report has shown that regulatory T cells (Treg) were markedly more sensitive to adenosine-5'-triphosphate (ATP) than conventional T cells (Tconv). Another one has shown that Tregs and CD45RBlowTconvs, but not CD45RBhighTconvs, displayed similar high sensitivity to ATP. We have previously reported that CD45RBlowTconvs expressing B220/CD45RABC molecules in a pre-apoptotic stage are resistant to ATP stimulation due to the loss of P2X7 receptor (P2X7R) membrane expression. To gain a clearer picture on T-cell sensitivity to ATP, we have quantified four different cellular activities triggered by ATP in mouse T cells at different stages of activation/differentiation, in correlation with levels of P2X7R membrane expression. P2X7R expression significantly increases on Tconvs during differentiation from naive CD45RBhighCD44lowto effector/memory CD45RBlowCD44highstage. Maximum levels of upregulation are reached on recently activated CD69+naive and memory Tconvs. Ectonucleotidases CD39 and CD73 expression levels increase in parallel with those of P2X7R. Recently activated CD69+CD45RBhighCD44lowTconvs, although expressing high levels of P2X7R, fail to cleave homing receptor CD62L after ATP treatment, but efficiently form pores and externalize phosphatidylserine (PS). In contrast, naive CD45RBhighCD44lowTconvs cleave CD62L with high efficiency although they express a lower level of P2X7, thus suggesting that P2X7R levels are not a limiting factor for signaling ATP-induced cellular responses. Contrary to common assumption, P2X7R-mediated cellular activities in mouse Tconvs are not triggered in an all-or-none manner, but depend on their stage of activation/differentiation. Compared to CD45RBlowTconvs, CD45RBlowFoxp3+Tregs show significantly higher levels of P2X7R membrane expression and of sensitivity to ATP as evidenced by their high levels of CD62L shedding, pore formation and PS externalization observed after ATP treatment. In summary, the different abilities of ATP-treated Tconvs to form pore or cleave CD62L depending on their activation and differentiation state suggests that P2X7R signaling varies according to the physiological role of T convs during antigen activation in secondary lymphoid organs or trafficking to inflammatory sites.
    Mots-clés : B3S, CD39, CD62L shedding, CD73, cell death, MIP, P2X7, phosphatidyslerine exposure, pore formation, regulatory T lymphocyte.


  • R. R. Sonani, A. Gardiner, R. P. Rastogi, R. Cogdell, B. Robert, et D. Madamwar, « Site, trigger, quenching mechanism and recovery of non-photochemical quenching in cyanobacteria: recent updates », Photosynthesis Research, mars 2018.

  • C. Tellier-Lebegue, E. Dizet, E. Ma, X. Veaute, E. Coïc, J. - B. Charbonnier, et L. Maloisel, « Correction: The translesion DNA polymerases Pol ζ and Rev1 are activated independently of PCNA ubiquitination upon UV radiation in mutants of DNA polymerase δ », PLoS genetics, vol. 14, nᵒ 2, p. e1007236, févr. 2018.
    Résumé : [This corrects the article DOI: 10.1371/journal.pgen.1007119.].
    Mots-clés : B3S, INTGEN.


  • T. - T. Tran, M. - H. Ha-Thi, T. Pino, A. Quaranta, C. Lefumeux, W. Leibl, et A. Aukauloo, « Snapshots of Light Induced Accumulation of Two Charges on Methylviologen using a Sequential Nanosecond Pump–Pump Photoexcitation », The Journal of Physical Chemistry Letters, vol. 9, nᵒ 5, p. 1086-1091, 2018.

  • S. P. Visweshwaran, P. A. Thomason, R. Guerois, S. Vacher, E. V. Denisov, L. A. Tashireva, M. E. Lomakina, C. Lazennec-Schurdevin, G. Lakisic, S. Lilla, N. Molinie, V. Henriot, Y. Mechulam, A. Y. Alexandrova, N. V. Cherdyntseva, I. Bièche, E. Schmitt, R. H. Insall, et A. Gautreau, « The trimeric coiled-coil HSBP1 protein promotes WASH complex assembly at centrosomes », The EMBO journal, mai 2018.
    Résumé : The Arp2/3 complex generates branched actin networks that exert pushing forces onto different cellular membranes. WASH complexes activate Arp2/3 complexes at the surface of endosomes and thereby fission transport intermediates containing endocytosed receptors, such as α5β1 integrins. How WASH complexes are assembled in the cell is unknown. Here, we identify the small coiled-coil protein HSBP1 as a factor that specifically promotes the assembly of a ternary complex composed of CCDC53, WASH, and FAM21 by dissociating the CCDC53 homotrimeric precursor. HSBP1 operates at the centrosome, which concentrates the building blocks. HSBP1 depletion in human cancer cell lines and in Dictyostelium amoebae phenocopies WASH depletion, suggesting a critical role of the ternary WASH complex for WASH functions. HSBP1 is required for the development of focal adhesions and of cell polarity. These defects impair the migration and invasion of tumor cells. Overexpression of HSBP1 in breast tumors is associated with increased levels of WASH complexes and with poor prognosis for patients.
    Mots-clés : actin cytoskeleton, AMIG, Arp2/3 complex, B3S, cell migration and invasion, centrosome, multiprotein complex assembly.

2017


  • A. M. Acuña, C. Lemaire, R. van Grondelle, B. Robert, et I. H. M. van Stokkum, « Energy transfer and trapping in Synechococcus WH 7803 », Photosynthesis Research, oct. 2017.
    Résumé : Excitation energy transfer (EET) and trapping in Synechococcus WH 7803 whole cells and isolated photosystem I (PSI) complexes have been studied by time-resolved emission spectroscopy at room temperature (RT) and at 77 K. With the help of global and target analysis, the pathways of EET and the charge separation dynamics have been identified. Energy absorbed in the phycobilisome (PB) rods by the abundant phycoerythrin (PE) is funneled to phycocyanin (PC645) and from there to the core that contains allophycocyanin (APC660 and APC680). Intra-PB EET rates have been estimated to range from 11 to 68/ns. It was estimated that at RT, the terminal emitter of the phycobilisome, APC680, transfers its energy at a rate of 90/ns to PSI and at a rate of 50/ns to PSII. At 77 K, the redshifted Chl a states in the PSI core were heterogeneous, with maximum emission at 697 and 707 nm. In 72% of the PSI complexes, the bulk Chl a in equilibrium with F697 decayed with a main trapping lifetime of 39 ps.
    Mots-clés : B3S, Excitation energy transfer, Global analysis, LBMS, Light harvesting, LPSM, Target analysis.


  • M. Amjadi, T. Hallaj, H. Asadollahi, Z. Song, M. de Frutos, et N. Hildebrandt, « Facile synthesis of carbon quantum dot/silver nanocomposite and its application for colorimetric detection of methimazole », Sensors and Actuators B: Chemical, vol. 244, p. 425-432, 2017.


  • H. Azouaoui, C. Montigny, T. Dieudonné, P. Champeil, A. Jacquot, J. L. Vázquez-Ibar, P. Le Maréchal, J. Ulstrup, M. - R. Ash, J. A. Lyons, P. Nissen, et G. Lenoir, « A High and Phosphatidylinositol-4-phosphate (PI4P)-dependent ATPase Activity for the Drs2p/Cdc50p Flippase after Removal of its N- and C-terminal Extensions », Journal of Biological Chemistry, p. jbc.M116.751487, mars 2017.
    Mots-clés : autophosphorylation, B3S, Cdc50 protein, Flippase, inhibition mechanism, limited proteolysis, lipid-protein interaction, LPSM, phosphatidylserine, phosphoinositide.

  • A. Bahloul, E. Pepermans, B. Raynal, N. Wolff, F. Cordier, P. England, S. Nouaille, B. Baron, A. El-Amraoui, J. - P. Hardelin, D. Durand, et C. Petit, « Conformational switch of harmonin, a submembrane scaffold protein of the hair cell mechanoelectrical transduction machinery », FEBS letters, juin 2017.
    Résumé : Mutations in the gene encoding harmonin, a multi-PDZ domain-containing submembrane protein, cause Usher syndrome type 1 (congenital deafness and balance disorder, as well as early-onset sight loss). The structure of the protein and biological activities of its three different classes of splice isoforms (a, b, and c) remain poorly understood. Combining biochemical and biophysical analyses, we show that harmonin-a1 can switch between open and closed conformations through intramolecular binding of its C-terminal PDZ-binding motif to its N-terminal supramodule NTD-PDZ1 and a flexible PDZ2-PDZ3 linker. This conformational switch presumably extends to most harmonin isoforms, and is expected to have an impact on the interaction with some binding partners, as shown here for cadherin-related 23, another component of the hair cell mechanoelectrical transduction machinery. This article is protected by copyright. All rights reserved.
    Mots-clés : B3S, conformation switch, FAAM, PDZ domain, Usher syndrome.


  • E. Baquero, A. A. Albertini, H. Raux, A. Abou‐Hamdan, E. Boeri‐Erba, M. Ouldali, L. Buonocore, J. K. Rose, J. Lepault, S. Bressanelli, et Y. Gaudin, « Structural intermediates in the fusion‐associated transition of vesiculovirus glycoprotein », The EMBO Journal, vol. 36, nᵒ 5, p. 679-692, mars 2017.
    Mots-clés : B3S, conformational change, glycoprotein, IMAPP, intermediate structures, membrane fusion, RHABDO, Vesiculovirus, VIRO, VIROEM.

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