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Publications de l’I2BC


  • A. Agorio, J. Giraudat, M. W. Bianchi, J. Marion, C. Espagne, L. Castaings, F. Lelièvre, C. Curie, S. Thomine, et S. Merlot, « Phosphatidylinositol 3-phosphate–binding protein AtPH1 controls the localization of the metal transporter NRAMP1 in Arabidopsis », Proceedings of the National Academy of Sciences, p. 201702975, avr. 2017.
    Mots-clés : BIOCELL, DYNBSJ, late endosome, metal transport, MINION, NRAMP, phosphatidylinositol 3-phosphate, vacuole.

  • S. Ait-El-Mkadem, M. Dayem-Quere, M. Gusic, A. Chaussenot, S. Bannwarth, B. François, E. C. Genin, K. Fragaki, C. L. M. Volker-Touw, C. Vasnier, V. Serre, K. L. I. van Gassen, F. Lespinasse, S. Richter, G. Eisenhofer, C. Rouzier, F. Mochel, A. De Saint-Martin, M. - T. Abi Warde, M. G. M. de Sain-van der Velde, J. J. M. Jans, J. Amiel, Z. Avsec, C. Mertes, T. B. Haack, T. Strom, T. Meitinger, P. E. Bonnen, R. W. Taylor, J. Gagneur, P. M. van Hasselt, A. Rötig, A. Delahodde, H. Prokisch, S. A. Fuchs, et V. Paquis-Flucklinger, « Mutations in MDH2, Encoding a Krebs Cycle Enzyme, Cause Early-Onset Severe Encephalopathy », American Journal of Human Genetics, vol. 100, nᵒ 1, p. 151-159, 2017.

  • A. K. Alame-Emane, C. Pierre-Audigier, O. C. Aboumegone-Biyogo, A. Nzoghe-Mveang, V. Cadet-Daniel, C. Sola, J. F. Djoba-Siawaya, B. Gicquel, et H. E. Takiff, « The use of GeneXpert remnants for drug resistance profiling and molecular epidemiology of tuberculosis in Libreville, Gabon », Journal of Clinical Microbiology, 2017.
    Résumé : Multidrug (MDR) and extensively drug resistant (XDR) Mycobacterium tuberculosis are major problems in global health. The GeneXpertMTB/RIF (Xpert) rapidly detects resistance to rifampicin (RIF-R), but detection of the additional resistance that defines MDR and XDR-TB, and for molecular epidemiology, specimen cultures and biosafe infrastructure are generally required. We sought to determine whether the remnants of sputa prepared for Xpert could be used directly to find mutations associated with drug resistance and for molecular epidemiology, and thus provide a precise characterization of MDR-TB cases in countries lacking BSL3 facilities for M. tuberculosis cultures. After sputa were processed and run on the Xpert instrument, the leftovers of the samples prepared for Xpert were used for PCR amplification and sequencing or line probe assay to detect mutations associated with resistance to additional drugs, and for molecular epidemiology with spoligotyping and selective MIRU-VNTR. Of 130 sputum samples from Gabon tested with Xpert, 124 yielded interpretable results, of which 21 were determined to be RIF-R (17%). Amplification and sequencing or line probe assay of the Xpert remnants confirmed 18/21 as MDR: 11/116 (9.5%) new and 7/8 (87%) previously treated TB patients. Spoligotyping and MIRU with hypervariable loci identified an MDR Beijing strain present in five samples. We conclude that the remnants of samples processed for Xpert in PCR reactions can be used to find mutations associated with the resistance to the additional drugs that define MDR and XDR-TB, and to study molecular epidemiology without the need for culturing or biosafe infrastructure.
    Mots-clés : IGEPE, MICROBIO.

  • 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.

  • A. F. Amorim, D. Pinto, L. Kuras, et L. Fernandes, « Absence of Gim proteins, but not GimC complex, alter stress-induced transcription », Biochimica Et Biophysica Acta, 2017.
    Résumé : Saccharomyces cerevisiae GimC (mammalian Prefoldin) is a hexameric (Gim1-6) cytoplasmic complex involved in the folding pathway of actin/tubulin. In contrast to a shared role in GimC complex, we show that absence of individual Gim proteins results in distinct stress responses. No concomitant alteration in F-actin integrity was observed. Transcription of stress responsive genes is altered in gim2Δ, gim3Δ and gim6Δ mutants: TRX2 gene is induced in these mutants but with a profile diverging from type cells, whereas CTT1 and HSP26 fail to be induced. Remaining gimΔ mutants display stress transcript abundance comparable to wild type cells. No alteration in the nuclear localization of the transcriptional activators for TRX2 (Yap1) and CTT1/HSP26 (Msn2) was observed in gim2Δ. In accordance with TRX2 induction, RNA polymerase II occupancy at TRX2 discriminates the wild type from gim2Δ and gim6Δ. In contrast, RNA polymerase II occupancy at CTT1 is similar in wild type and gim2Δ, but higher in gim6Δ. The absence of active RNA polymerase II at CTT1 in gim2Δ, but not in wild type and gim1Δ, explains the respective CTT1 transcript outputs. Altogether our results put forward the need of Gim2, Gim3 and Gim6 in oxidative and osmotic stress activated transcription; others Gim proteins are dispensable. Consequently, the participation of Gim proteins in activated-transcription is independent from the GimC complex.
    Mots-clés : DBG, Gim proteins, PEPS, stress, Transcription regulation.

  • A. Arnal, C. Jacqueline, B. Ujvari, L. Leger, C. Moreno, D. Faugere, A. Tasiemski, C. Boidin-Wichlacz, D. Misse, F. Renaud, J. Montagne, A. Casali, B. Roche, F. Mery, et F. Thomas, « Cancer brings forward oviposition in the fly Drosophila melanogaster », Ecology and Evolution, vol. 7, nᵒ 1, p. 272-276, 2017.
    Résumé : Hosts often accelerate their reproductive effort in response to a parasitic infection, especially when their chances of future reproduction decrease with time from the onset of the infection. Because malignancies usually reduce survival, and hence potentially the fitness, it is expected that hosts with early cancer could have evolved to adjust their life-history traits to maximize their immediate reproductive effort. Despite the potential importance of these plastic responses, little attention has been devoted to explore how cancers influence animal reproduction. Here, we use an experimental setup, a colony of genetically modified flies Drosophila melanogaster which develop colorectal cancer in the anterior gut, to show the role of cancer in altering life-history traits. Specifically, we tested whether females adapt their reproductive strategy in response to harboring cancer. We found that flies with cancer reached the peak period of oviposition significantly earlier (i.e., 2 days) than healthy ones, while no difference in the length and extent of the fecundity peak was observed between the two groups of flies. Such compensatory responses to overcome the fitness-limiting effect of cancer could explain the persistence of inherited cancer-causing mutant alleles in the wild.
    Mots-clés : BIOCELL, cancer, fecundity, life‐history strategy, METABO, reproduction.

  • A. Aubusson-Fleury, G. Balavoine, M. Lemullois, K. Bouhouche, J. Beisson, et F. Koll, « Centrin diversity and basal body patterning across evolution: new insights from Paramecium », Biology Open, 2017.
    Résumé : First discovered in unicellular eukaryotes, centrins play crucial roles in basal body duplication and anchoring mechanisms. While the evolutionary status of the founding members of the family, Centrin2/Vfl2 and Centrin3/cdc31 has long been investigated, the evolutionary origin of other members of the family has received less attention. Using a phylogeny of ciliate centrins, we identify two other centrin families, the ciliary centrins and the centrins present in the contractile filaments (ICL centrins). In this paper, we carry on the functional analysis of still not well known centrins, the ICL1e subfamily identified in Paramecium, and show their requirement for correct basal body anchoring through interactions with Centrin2 and Centrin3. Using Paramecium as well as an Eukaryote-wide sampling of centrins from completely sequenced genomes, we revisited the evolutionary story of centrins. Their phylogeny shows that the centrins associated with the ciliate contractile filaments are widespread in eukaryotic lineages and could be as ancient as Centrin2 and Centrin3.
    Mots-clés : basal body anchoring, basal body assembly, BIOCELL, BIOCIL, centrin evolution, Ciliary centrins, ciliated epithelia polarity.

  • 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.

  • 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.

  • S. Barral, Y. Morozumi, H. Tanaka, E. Montellier, J. Govin, M. de Dieuleveult, G. Charbonnier, Y. Couté, D. Puthier, T. Buchou, F. Boussouar, T. Urahama, F. Fenaille, S. Curtet, P. Héry, N. Fernandez-Nunez, H. Shiota, M. Gérard, S. Rousseaux, H. Kurumizaka, et S. Khochbin, « Histone Variant H2A.L.2 Guides Transition Protein-Dependent Protamine Assembly in Male Germ Cells », Molecular Cell, vol. 66, nᵒ 1, p. 89-101.e8, 2017.

  • H. Bengueddach, M. Lemullois, A. Aubusson-Fleury, et F. Koll, « Basal body positioning and anchoring in the multiciliated cell Paramecium tetraurelia: roles of OFD1 and VFL3 », Cilia, vol. 6, nᵒ 1, 2017.

  • L. Bidou, O. Bugaud, V. Belakhov, T. Baasov, et O. Namy, « Characterization of new-generation aminoglycoside promoting premature termination codon readthrough in cancer cells », RNA biology, p. 1-11, 2017.
    Résumé : Nonsense mutations, generating premature termination codons (PTCs), account for 10% to 30% of the mutations in tumor suppressor genes. Nonsense translational suppression, induced by small molecules including gentamicin and G418, has been suggested as a potential therapy to counteract the deleterious effects of nonsense mutations in several genetic diseases and cancers. We describe here that NB124, a synthetic aminoglycoside derivative recently developed especially for PTC suppression, strongly induces apoptosis in human tumor cells by promoting high level of PTC readthrough. Using a reporter system, we showed that NB124 suppressed several of the PTCs encountered in tumor suppressor genes, such as the p53 and APC genes. We also showed that NB124 counteracted p53 mRNA degradation by nonsense-mediated decay (NMD). Both PTC suppression and mRNA stabilization contributed to the production of a full-length p53 protein capable of activating p53-dependent genes, thereby specifically promoting high levels of apoptosis. This new-generation aminoglycoside thus outperforms the only clinically available readthrough inducer (gentamicin). These results have important implications for the development of personalised treatments of PTC-dependent diseases and for the development of new drugs modifying translation fidelity.
    Mots-clés : Aminoglycoside, Apoptosis, cancer, DBG, GST, p53, stop codon readthrough.

  • W. V. Bienvenut, J. - P. Scarpelli, J. Dumestier, T. Meinnel, et C. Giglione, « EnCOUNTer: a parsing tool to uncover the mature N-terminus of organelle-targeted proteins in complex samples », BMC Bioinformatics, vol. 18, nᵒ 1, 2017.
    Mots-clés : DBG, DIR, PROMTI, SICS.

  • K. Bodvard, K. Peeters, F. Roger, N. Romanov, A. Igbaria, N. Welkenhuysen, G. Palais, W. Reiter, M. B. Toledano, M. Käll, et M. Molin, « Light-sensing via hydrogen peroxide and a peroxiredoxin », Nature Communications, vol. 8, p. 14791, mars 2017.

  • M. Bosco, A. Massarweh, S. Iatmanen-Harbi, A. Bouhss, I. Chantret, P. Busca, S. E. H. Moore, et C. Gravier-Pelletier, « Synthesis and biological evaluation of chemical tools for the study of Dolichol Linked Oligosaccharide Diphosphatase (DLODP) », European Journal of Medicinal Chemistry, vol. 125, p. 952-964, 2017.
    Résumé : Citronellyl- and solanesyl-based dolichol linked oligosaccharide (DLO) analogs were synthesized and tested along with undecaprenyl compounds for their ability to inhibit the release of [(3)H]OSP from [(3)H]DLO by mammalian liver DLO diphosphatase activity. Solanesyl (C45) and undecaprenyl (C55) compounds were 50-500 fold more potent than their citronellyl (C10)-based counterparts, indicating that the alkyl chain length is important for activity. The relative potency of the compounds within the citronellyl series was different to that of the solanesyl series with citronellyl diphosphate being 2 and 3 fold more potent than citronellyl-PP-GlcNAc2 and citronellyl-PP-GlcNAc, respectively; whereas solanesyl-PP-GlcNAc and solanesyl-PP-GlcNAc2 were 4 and 8 fold more potent, respectively, than solanesyl diphosphate. Undecaprenyl-PP-GlcNAc and bacterial Lipid II were 8 fold more potent than undecaprenyl diphosphate at inhibiting the DLODP assay. Therefore, at least for the more hydrophobic compounds, diphosphodiesters are more potent inhibitors of the DLODP assay than diphosphomonoesters. These results suggest that DLO rather than dolichyl diphosphate might be a preferred substrate for the DLODP activity.
    Mots-clés : Animals, Biological evaluation, CDG, Diphosphatase, Disubstituted diphosphates, Dolichol, Dolichol Phosphates, ENVBAC, Glycochemistry, Humans, liver, MICROBIO, Monoterpenes, Oligosaccharides, Phosphoric Diester Hydrolases, Phosphoric Monoester Hydrolases, Phosphosugars, Polyisoprenyl Phosphate Sugars, Polyisoprenyl Phosphates, Substrate Specificity.

  • V. Bouchez, S. AlBitar-Nehmé, A. Novikov, N. Guiso, et M. Caroff, « Bordetella holmesii: Lipid A Structures and Corresponding Genomic Sequences Comparison in Three Clinical Isolates and the Reference Strain ATCC 51541 », International Journal of Molecular Sciences, vol. 18, nᵒ 5, 2017.
    Résumé : Bordetella holmesii can cause invasive infections but can also be isolated from the respiratory tract of patients with whooping-cough like symptoms. For the first time, we describe the lipid A structure of B. holmesii reference strain ATCC 51541 (alias NCTC12912 or CIP104394) and those of three French B. holmesii clinical isolates originating from blood (Bho1) or from respiratory samples (FR4020 and FR4101). They were investigated using chemical analyses, gas chromatography-mass spectrometry (GC-MS), and matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS). The analyses revealed a common bisphosphorylated β-(1→6)-linked d-glucosamine disaccharide with hydroxytetradecanoic acid in amide linkages. Similar to B. avium, B. hinzii and B. trematum lipids A, the hydroxytetradecanoic acid at the C-2' position are carrying in secondary linkage a 2-hydroxytetradecanoic acid residue resulting of post-traductional biosynthesis modifications. The three clinical isolates displayed characteristic structural traits compared to the ATCC 51541 reference strain: the lipid A phosphate groups are more or less modified with glucosamine in the isolates and reference strain, but the presence of 10:0(3-OH) is only observed in the isolates. This trait was only described in B. pertussis and B. parapertussis strains, as well as in B. petrii isolates by the past. The genetic bases for most of the key structural elements of lipid A were analyzed and supported the structural data.
    Mots-clés : Bordetella holmesii, Bordetellae, CAROFF, DIR, Endotoxin, genomic, Lipid A, Mass Spectrometry, structure.

  • M. Boudard, D. Barth, J. Bernauer, A. Denise, et J. Cohen, « GARN2: coarse-grained prediction of 3D structure of large RNA molecules by regret minimization », Bioinformatics (Oxford, England), 2017.
    Résumé : Motivation: Predicting the 3D structure of RNA molecules is a key feature towards predicting their functions. Methods which work at atomic or nucleotide level are not suitable for large molecules. In these cases, coarse-grained prediction methods aim to predict a shape which could be refined later by using more precise methods on smaller parts of the molecule. Results: We developed a complete method for sampling 3D RNA structure at a coarse-grained model, taking a secondary structure as input. One of the novelties of our method is that a second step extracts two best possible structures close to the native, from a set of possible structures. Although our method benefits from the first version of GARN, some of the main features on GARN2 are very different. GARN2 is much faster than the previous version and than the well-known methods of the state-of-art. Our experiments show that GARN2 can also provide better structures than the other state-of-the-art methods. Availability and implementations: GARN2 is written in Java. It is freely distributed and available at: . Contacts: , Supplementary information: Supplementary data are available at Bioinformatics online.
    Mots-clés : BIM, DBG.

  • C. Bouthier de la Tour, M. Mathieu, L. Meyer, P. Dupaigne, F. Passot, P. Servant, S. Sommer, E. Le Cam, et F. Confalonieri, « In vivo and in vitro characterization of DdrC, a DNA damage response protein in Deinococcus radiodurans bacterium », PloS One, vol. 12, nᵒ 5, p. e0177751, 2017.
    Résumé : The bacterium Deinococcus radiodurans possesses a set of Deinococcus-specific genes highly induced after DNA damage. Among them, ddrC (dr0003) was recently re-annotated, found to be in the inverse orientation and called A2G07_00380. Here, we report the first in vivo and in vitro characterization of the corrected DdrC protein to better understand its function in irradiated cells. In vivo, the ΔddrC null mutant is sensitive to high doses of UV radiation and the ddrC deletion significantly increases UV-sensitivity of ΔuvrA or ΔuvsE mutant strains. We show that the expression of the DdrC protein is induced after γ-irradiation and is under the control of the regulators, DdrO and IrrE. DdrC is rapidly recruited into the nucleoid of the irradiated cells. In vitro, we show that DdrC is able to bind single- and double-stranded DNA with a preference for the single-stranded DNA but without sequence or shape specificity and protects DNA from various nuclease attacks. DdrC also condenses DNA and promotes circularization of linear DNA. Finally, we show that the purified protein exhibits a DNA strand annealing activity. Altogether, our results suggest that DdrC is a new DNA binding protein with pleiotropic activities. It might maintain the damaged DNA fragments end to end, thus limiting their dispersion and extensive degradation after exposure to ionizing radiation. DdrC might also be an accessory protein that participates in a single strand annealing pathway whose importance in DNA repair becomes apparent when DNA is heavily damaged.
    Mots-clés : DBG, RBA.

  • A. Breton, A. Novikov, R. Martin, P. Tissieres, et M. Caroff, « Structural and biological characteristics of different forms of V. filiformis lipid A: use of MS to highlight structural discrepancies », Journal of Lipid Research, vol. 58, nᵒ 3, p. 543-552, 2017.
    Résumé : Vitreoscilla filiformis is a Gram-negative bacterium isolated from spa waters and described for its beneficial effects on the skin. We characterized the detailed structure of its lipopolysaccharide (LPS) lipid A moiety, an active component of the bacterium that contributes to the observed skin activation properties. Two different batches differing in postculture cell recovery were tested. Chemical analyses and mass spectra, obtained before and after mild-alkali treatments, revealed that these lipids A share the common bisphosphorylated β-(1→6)-linked d-glucosamine disaccharide with hydroxydecanoic acid in an amide linkage. Short-chain FAs, hydroxydecanoic and dodecanoic acid, were found in a 2:1 ratio. The two lipid A structures differed by the relative amount of the hexa-acyl molecular species and phosphoethanolamine substitution of the phosphate groups. The two V. filiformis LPS batches induced variable interleukin-6 and TNF-α secretion by stimulated myelomonocytic THP-1 cells, without any difference in reactive oxygen species production or activation of caspase 3/7. Other different well-known highly purified LPS samples were characterized structurally and used as standards. The structural data obtained in this work explain the low inflammatory response observed for V. filiformis LPS and the previously demonstrated beneficial effects on the skin.
    Mots-clés : cytokines, ESHR, lipid biochemistry, lipopolysaccharide, Mass Spectrometry, MICROBIO, skin, Toll-like receptor, V. filiformis.

  • S. C. Brown, M. Bourge, N. Maunoury, M. Wong, M. W. Bianchi, S. Lepers-Andrzejewski, P. Besse, S. Siljak-Yakovlev, M. Dron, et B. Satiat-Jeunemaître, « DNA remodelling by Strict Partial Endoreplication in orchids, an original process in the plant kingdom », Genome Biology and Evolution, 2017.
    Résumé : DNA remodelling during endoreplication appears to be a strong developmental characteristic in orchids. In this study, we analysed DNA content and nuclei in 41 species of orchids to further map the genome evolution in this plant family. We demonstrate that the DNA remodelling observed in 36 out of 41 orchids studied corresponds to strict partial endoreplication. Such process is developmentally regulated in each wild species studied. Cytometry data analyses allowed us to propose a model where nuclear states 2C, 4E, 8E, etc. form a series comprising a fixed proportion, the euploid genome 2C, plus 2 to 32 additional copies of a complementary part of the genome. The fixed proportion ranged from 89% of the genome in Vanilla mexicana down to 19% in V. pompona, the lowest value for all 148 orchids reported. Insterspecific hybridisation did not suppress this phenomenon. Interestingly, this process was not observed in mass-produced epiphytes. Nucleolar volumes grow with the number of endocopies present, coherent with high transcription activity in endoreplicated nuclei. Our analyses suggest species-specific chromatin rearrangement. Towards understanding endoreplication, V. planifolia constitutes a tractable system for isolating the genomic sequences that confer an advantage via endoreplication from those that apparently suffice at diploid level.
    Mots-clés : BIOCELL, CYTO, cytogenetics, cytometry, DYNBSJ, endoreplication, genome imbalance, Genome Size, PF, Vanilla.

  • S. Bury-Moné et B. Sclavi, « Stochasticity of gene expression as a motor of epigenetics in bacteria: from individual to collective behavior », Research in Microbiology, 2017.
    Résumé : Measuring gene expression at the single cell and single molecule level has recently made possible the quantitative measurement of stochasticity of gene expression. This enables identification of the probable sources and roles of noise. Stochastic gene expression can result in bacterial population heterogeneity, offering specific advantages for fitness and survival in various environments. This trait is therefore selected during the evolution of the species, and is consequently regulated by specific genetic network architecture. Examples exist in stress-response mechanisms, as well as in infection and pathogenicity strategies, pointing to advantages for multicellularity of bacterial populations.
    Mots-clés : ACTINO, Behavior, Bi-stability, Epigenetics, gene expression, MICROBIO, Multicellularity, regulatory networks, Stochasticity.

  • S. E. Cannella, V. Y. Ntsogo Enguéné, M. Davi, C. Malosse, A. C. Sotomayor Pérez, J. Chamot-Rooke, P. Vachette, D. Durand, D. Ladant, et A. Chenal, « Stability, structural and functional properties of a monomeric, calcium–loaded adenylate cyclase toxin, CyaA, from Bordetella pertussis », Scientific Reports, vol. 7, p. 42065, févr. 2017.

  • L. Cao, S. Cantos-Fernandes, et B. Gigant, « The structural switch of nucleotide-free kinesin », Scientific Reports, vol. 7, p. 42558, févr. 2017.

  • M. - F. Carlier et S. Shekhar, « Global treadmilling coordinates actin turnover and controls the size of actin networks », Nature Reviews Molecular Cell Biology, mars 2017.

  • C. Cassier-Chauvat, V. Dive, et F. Chauvat, « Cyanobacteria: photosynthetic factories combining biodiversity, radiation resistance, and genetics to facilitate drug discovery », Applied Microbiology and Biotechnology, vol. 101, nᵒ 4, p. 1359-1364, 2017.
    Résumé : Cyanobacteria are ancient, abundant, and widely diverse photosynthetic prokaryotes, which are viewed as promising cell factories for the ecologically responsible production of chemicals. Natural cyanobacteria synthesize a vast array of biologically active (secondary) metabolites with great potential for human health, while a few genetic models can be engineered for the (low level) production of biofuels. Recently, genome sequencing and mining has revealed that natural cyanobacteria have the capacity to produce many more secondary metabolites than have been characterized. The corresponding panoply of enzymes (polyketide synthases and non-ribosomal peptide synthases) of interest for synthetic biology can still be increased through gene manipulations with the tools available for the few genetically manipulable strains. In this review, we propose to exploit the metabolic diversity and radiation resistance of cyanobacteria, and when required the genetics of model strains, for the production and radioactive ((14)C) labeling of bioactive products, in order to facilitate the screening for new drugs.
    Mots-clés : B2CYA, Biodiversity, Cyanobacteria, MICROBIO, Peptide Synthases, photosynthesis, Radioactive labeling, Secondary metabolites, Toxins.

  • V. Chaptal, F. Delolme, A. Kilburg, S. Magnard, C. Montigny, M. Picard, C. Prier, L. Monticelli, O. Bornert, M. Agez, S. Ravaud, C. Orelle, R. Wagner, A. Jawhari, I. Broutin, E. Pebay-Peyroula, J. - M. Jault, H. R. Kaback, M. le Maire, et P. Falson, « Quantification of Detergents Complexed with Membrane Proteins », Scientific Reports, vol. 7, p. 41751, févr. 2017.

  • J. - P. Charbonnier, E. M. van Rikxoort, A. A. A. Setio, C. M. Schaefer-Prokop, B. van Ginneken, et F. Ciompi, « Improving airway segmentation in computed tomography using leak detection with convolutional networks », Medical Image Analysis, vol. 36, p. 52-60, 2017.

  • S. Chardonnet, T. Bessiron, C. I. Ramos, R. Dammak, M. - A. Richard, C. Boursier, C. Cadillac, F. M. Coquelle, S. Bossi, F. Ango, P. Le Maréchal, P. Decottignies, C. Berrier, H. McLean, et H. Daniel, « Native metabotropic glutamate receptor 4 depresses synaptic transmission through an unusual Gαq transduction pathway », Neuropharmacology, 2017.
    Résumé : In cerebellar cortex, mGlu4 receptors located on parallel fibers play an essential role in normal motor function, but the molecular mechanisms involved are not yet completely understood. Using a strategy combining biochemical and electrophysiological approaches in the rodent cerebellum, we demonstrate that presynaptic mGlu4 receptors control synaptic transmission through an atypical activation of Gαq proteins. First, the Gαq subunit, PLC and PKC signaling proteins present in cerebellar extracts are retained on affinity chromatography columns grafted with different sequences of the cytoplasmic domain of mGlu4 receptor. The i2 loop and the C terminal domain were used as baits, two domains that are known to play a pivotal role in coupling selectivity and efficacy. Second, in situ proximity ligation assays show that native mGlu4 receptors and Gαq subunits are in close physical proximity in cerebellar cortical slices. Finally, electrophysiological experiments demonstrate that the molecular mechanisms underlying mGlu4 receptor-mediated inhibition of transmitter release at cerebellar Parallel Fiber (PF) - Molecular Layer Interneuron (MLI) synapses involves the Gαq-PLC signaling pathway. Taken together, our results provide compelling evidence that, in the rodent cerebellar cortex, mGlu4 receptors act by coupling to the Gαq protein and PLC effector system to reduce glutamate synaptic transmission.
    Mots-clés : BIOCELL, Cerebellar cortex, DYNBSJ, G protein, Molecular layer interneurons, Presynaptic metabotropic glutamate receptor 4, Signaling pathway, Synaptic transmission.

  • R. Chouari, M. Leonard, M. Bouali, S. Guermazi, N. Rahli, I. Zrafi, L. Morin, et A. Sghir, « Eukaryotic molecular diversity at different steps of the wastewater treatment plant process reveals more phylogenetic novel lineages », World Journal of Microbiology & Biotechnology, vol. 33, nᵒ 3, p. 44, 2017.
    Résumé : Wastewater microbiota represents important actors of organic depollution. Nowadays, some species used as bioindicators of the effluent quality are still identified by microscopy. In the present study, we investigated eukaryotic diversity at the different steps of the treatment process of a wastewater treatment plant (aerobic, anaerobic, clarifier basins and anaerobic digester) using the 18S rRNA gene sequencing approach. Of the 1519 analysed sequences, we identified 160 operational taxonomic units. Interestingly, 56.9% of the phylotypes were assigned to novel phylogenetic molecular species since they show <97% sequence identity with their nearest affiliated representative within public databases. Peritrichia ciliates were the most predominant group, with Epistylis as the most common genus. Although anaerobic, the digester appears to harbor many unclassified phylotypes of protozoa species. Novel lineages such as LKM11 and LKM118 were widely represented in the digester. Diversity values given by Shannon indexes show that the clarifier is the most diversified. This work will help designing molecular tools that are fast, reliable, and reproducible for monitoring wastewater depollution and studying phylogenetic relationships among the wonderful world of protists within this anthropogenic ecosystem.
    Mots-clés : 18S rRNA gene, Activated sludge, Ciliates, Cryptomycota, LGBMB, LKM118, MICROBIO, Wastewater microbiota.

  • M. Clémancey, T. Cantat, G. Blondin, J. - M. Latour, P. Dorlet, et G. Lefèvre, « Structural Insights into the Nature of Fe(0) and Fe(I) Low-Valent Species Obtained upon the Reduction of Iron Salts by Aryl Grignard Reagents », Inorganic Chemistry, vol. 56, nᵒ 7, p. 3834-3848, 2017.
    Résumé : Mechanistic studies of the reduction of Fe(III) and Fe(II) salts by aryl Grignard reagents in toluene/tetrahydrofuran mixtures in the absence of a supporting ligand, as well as structural insights regarding the nature of the low-valent iron species obtained at the end of this reduction process, are reported. It is shown that several reduction pathways can be followed, depending on the starting iron precursor. We demonstrate, moreover, that these pathways lead to a mixture of Fe(0) and Fe(I) complexes regardless of the nature of the precursor. Mössbauer and (1)H NMR spectroscopies suggest that diamagnetic 16-electron bisarene complexes such as (η(4)-C6H5Me)2Fe(0) can be formed as major species (85% of the overall iron quantity). The formation of a η(6)-arene-ligated low-spin Fe(I) complex as a minor species (accounting for ca. 15% of the overall iron quantity) is attested by Mössbauer spectroscopy, as well as by continuous-wave electron paramagnetic resonance (EPR) and pulsed-EPR (HYSCORE) spectroscopies. The nature of the Fe(I) coordination sphere is discussed by means of isotopic labeling experiments and density functional theory calculations. It is shown that the most likely low-spin Fe(I) candidate obtained in these systems is a diphenylarene-stabilized species [(η(6)-C6H5Me)Fe(I)Ph2](-) exhibiting an idealized C2v topology. This enlightens the nature of the lowest valence states accommodated by iron during the reduction of Fe(III) and Fe(II) salts by aryl Grignard reagents in the absence of any additional coligand, which so far remained rather unknown. The reactivity of these low-valent Fe(I) and Fe(0) complexes in aryl-heteroaryl Kumada cross-coupling conditions has also been investigated, and it is shown that the zerovalent Fe(0) species can be used efficiently as a precursor in this reaction, whereas the Fe(I) oxidation state does not exhibit any reactivity.
    Mots-clés : B3S, LSOD.

  • K. Contrepois, C. Coudereau, B. A. Benayoun, N. Schuler, P. - F. Roux, O. Bischof, R. Courbeyrette, C. Carvalho, J. - Y. Thuret, Z. Ma, C. Derbois, M. - C. Nevers, H. Volland, C. E. Redon, W. M. Bonner, J. - F. Deleuze, C. Wiel, D. Bernard, M. P. Snyder, C. E. Rübe, R. Olaso, F. Fenaille, et C. Mann, « Histone variant H2A.J accumulates in senescent cells and promotes inflammatory gene expression », Nature Communications, vol. 8, p. 14995, 2017.
    Résumé : The senescence of mammalian cells is characterized by a proliferative arrest in response to stress and the expression of an inflammatory phenotype. Here we show that histone H2A.J, a poorly studied H2A variant found only in mammals, accumulates in human fibroblasts in senescence with persistent DNA damage. H2A.J also accumulates in mice with aging in a tissue-specific manner and in human skin. Knock-down of H2A.J inhibits the expression of inflammatory genes that contribute to the senescent-associated secretory phenotype (SASP), and over expression of H2A.J increases the expression of some of these genes in proliferating cells. H2A.J accumulation may thus promote the signalling of senescent cells to the immune system, and it may contribute to chronic inflammation and the development of aging-associated diseases.
    Mots-clés : DBG, SEN.

  • C. Cruciani-Guglielmacci, L. Bellini, J. Denom, M. Oshima, N. Fernandez, P. Normandie-Levi, X. P. Berney, N. Kassis, C. Rouch, J. Dairou, T. Gorman, D. M. Smith, A. Marley, R. Liechti, D. Kuznetsov, L. Wigger, F. Burdet, A. - L. Lefèvre, I. Wehrle, I. Uphues, T. Hildebrandt, W. Rust, C. Bernard, A. Ktorza, G. A. Rutter, R. Scharfmann, I. Xenarios, H. Le Stunff, B. Thorens, C. Magnan, et M. Ibberson, « Molecular phenotyping of multiple mouse strains under metabolic challenge uncovers a role for Elovl2 in glucose-induced insulin secretion », Molecular Metabolism, vol. 6, nᵒ 4, p. 340-351, 2017.

  • P. Cuniasse, P. Tavares, E. V. Orlova, et S. Zinn-Justin, « Structures of biomolecular complexes by combination of NMR and cryoEM methods », Current Opinion in Structural Biology, vol. 43, p. 104-113, 2017.

  • E. Dambroise, M. Simion, T. Bourquard, S. Bouffard, B. Rizzi, Y. Jaszczyszyn, M. Bourge, P. Affaticati, A. Heuzé, J. Jouralet, J. Edouard, S. Brown, C. Thermes, A. Poupon, E. Reiter, F. Sohm, F. Bourrat, et J. - S. Joly, « Postembryonic Fish Brain Proliferation Zones Exhibit Neuroepithelial-Type Gene Expression Profile: Features of Neuroepithelial Cells in Fish », STEM CELLS, 2017.
    Mots-clés : BMgif, CYTO, NGS, PF.

  • N. Dautin, C. de Sousa-d'Auria, F. Constantinesco-Becker, C. Labarre, J. Oberto, I. L. de la Sierra-Gallay, C. Dietrich, H. Issa, C. Houssin, et N. Bayan, « Mycoloyltransferases: A large and major family of enzymes shaping the cell envelope of Corynebacteriales », Biochimica et Biophysica Acta (BBA) - General Subjects, vol. 1861, nᵒ 1 Pt B, p. 3581-3592, 2017.
    Résumé : Mycobacterium and Corynebacterium are important genera of the Corynebacteriales order, the members of which are characterized by an atypical diderm cell envelope. Indeed the cytoplasmic membrane of these bacteria is surrounded by a thick mycolic acid-arabinogalactan-peptidoglycan (mAGP) covalent polymer. The mycolic acid-containing part of this complex associates with other lipids (mainly trehalose monomycolate (TMM) and trehalose dimycolate (TDM)) to form an outer membrane. The metabolism of mycolates in the cell envelope is governed by esterases called mycoloyltransferases that catalyze the transfer of mycoloyl chains from TMM to another TMM molecule or to other acceptors such as the terminal arabinoses of arabinogalactan or specific polypeptides. In this review we present an overview of this family of Corynebacteriales enzymes, starting with their expression, localization, structure and activity to finally discuss their putative functions in the cell. In addition, we show that Corynebacteriales possess multiple mycoloyltransferases encoding genes in their genome. The reason for this multiplicity is not known, as their function in mycolates biogenesis appear to be only partially redundant. It is thus possible that, in some species living in specific environments, some mycoloyltransferases have evolved to gain some new functions. In any case, the few characterized mycoloyltransferases are very important for the bacterial physiology and are also involved in adaptation in the host where they constitute major secreted antigens. Although not discussed in this review, all these functions make them interesting targets for the discovery of new antibiotics and promising vaccines candidates. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.
    Mots-clés : Antigen 85, ARCHEE, CORYNE, Esterase, Fibronectin-binding protein, MICROBIO, Mycobacterium, Mycolyltransferases, Mycomembrane.

  • R. P. de Vries, R. Riley, A. Wiebenga, G. Aguilar-Osorio, S. Amillis, C. A. Uchima, G. Anderluh, M. Asadollahi, M. Askin, K. Barry, E. Battaglia, Ö. Bayram, T. Benocci, S. A. Braus-Stromeyer, C. Caldana, D. Cánovas, G. C. Cerqueira, F. Chen, W. Chen, C. Choi, A. Clum, R. A. C. Dos Santos, A. R. de L. Damásio, G. Diallinas, T. Emri, E. Fekete, M. Flipphi, S. Freyberg, A. Gallo, C. Gournas, R. Habgood, M. Hainaut, M. L. Harispe, B. Henrissat, K. S. Hildén, R. Hope, A. Hossain, E. Karabika, L. Karaffa, Z. Karányi, N. Kraševec, A. Kuo, H. Kusch, K. LaButti, E. L. Lagendijk, A. Lapidus, A. Levasseur, E. Lindquist, A. Lipzen, A. F. Logrieco, A. MacCabe, M. R. Mäkelä, I. Malavazi, P. Melin, V. Meyer, N. Mielnichuk, M. Miskei, Á. P. Molnár, G. Mulé, C. Y. Ngan, M. Orejas, E. Orosz, J. P. Ouedraogo, K. M. Overkamp, H. - S. Park, G. Perrone, F. Piumi, P. J. Punt, A. F. J. Ram, A. Ramón, S. Rauscher, E. Record, D. M. Riaño-Pachón, V. Robert, J. Röhrig, R. Ruller, A. Salamov, N. S. Salih, R. A. Samson, E. Sándor, M. Sanguinetti, T. Schütze, K. Sepčić, E. Shelest, G. Sherlock, V. Sophianopoulou, F. M. Squina, H. Sun, A. Susca, R. B. Todd, A. Tsang, S. E. Unkles, N. van de Wiele, D. van Rossen-Uffink, J. V. de C. Oliveira, T. C. Vesth, J. Visser, J. - H. Yu, M. Zhou, M. R. Andersen, D. B. Archer, S. E. Baker, I. Benoit, A. A. Brakhage, G. H. Braus, R. Fischer, J. C. Frisvad, G. H. Goldman, J. Houbraken, B. Oakley, I. Pócsi, C. Scazzocchio, B. Seiboth, P. A. vanKuyk, J. Wortman, P. S. Dyer, et I. V. Grigoriev, « Comparative genomics reveals high biological diversity and specific adaptations in the industrially and medically important fungal genus Aspergillus », Genome Biology, vol. 18, nᵒ 1, p. 28, 2017.
    Résumé : BACKGROUND: The fungal genus Aspergillus is of critical importance to humankind. Species include those with industrial applications, important pathogens of humans, animals and crops, a source of potent carcinogenic contaminants of food, and an important genetic model. The genome sequences of eight aspergilli have already been explored to investigate aspects of fungal biology, raising questions about evolution and specialization within this genus. RESULTS: We have generated genome sequences for ten novel, highly diverse Aspergillus species and compared these in detail to sister and more distant genera. Comparative studies of key aspects of fungal biology, including primary and secondary metabolism, stress response, biomass degradation, and signal transduction, revealed both conservation and diversity among the species. Observed genomic differences were validated with experimental studies. This revealed several highlights, such as the potential for sex in asexual species, organic acid production genes being a key feature of black aspergilli, alternative approaches for degrading plant biomass, and indications for the genetic basis of stress response. A genome-wide phylogenetic analysis demonstrated in detail the relationship of the newly genome sequenced species with other aspergilli. CONCLUSIONS: Many aspects of biological differences between fungal species cannot be explained by current knowledge obtained from genome sequences. The comparative genomics and experimental study, presented here, allows for the first time a genus-wide view of the biological diversity of the aspergilli and in many, but not all, cases linked genome differences to phenotype. Insights gained could be exploited for biotechnological and medical applications of fungi.
    Mots-clés : Aspergillus, CLAUDIO, Comparative genomics, DIR, Fungal biology, Genome sequencing.

  • L. Dhers, N. Pietrancosta, L. Ducassou, B. Ramassamy, J. Dairou, M. Jaouen, F. André, D. Mansuy, et J. - L. Boucher, « Spectral and 3D model studies of the interaction of orphan human cytochrome P450 2U1 with substrates and ligands », Biochimica et Biophysica Acta (BBA) - General Subjects, vol. 1861, nᵒ 1, p. 3144-3153, 2017.

  • S. Di Gregorio, S. Fernandez, A. Cuirolo, O. Verlaine, A. Amoroso, D. Mengin-Lecreulx, A. Famiglietti, B. Joris, et M. Mollerach, « Different Vancomycin-Intermediate Staphylococcus aureus Phenotypes Selected from the Same ST100-hVISA Parental Strain », Microbial Drug Resistance (Larchmont, N.Y.), vol. 23, nᵒ 1, p. 44-50, 2017.
    Résumé : The aim of this study is to characterize the factors related to peptidoglycan metabolism in isogenic hVISA/VISA ST100 strains. Recently, we reported the increase in IS256 transposition in invasive hVISA ST100 clinical strains isolated from the same patient (D1 and D2) before and after vancomycin treatment and two laboratory VISA mutants (D23C9 and D2P11) selected from D2 in independent experiments. High performance liquid chromatography-mass spectrometry (HPLC-MS) analysis of peptidoglycan muropeptides showed increased proportion of monomeric muropeptides and a concomitant decrease in the proportion of tetrameric muropeptide in D2 and derived mutants when compared to the original strain D1. In addition, strain D2 and its derived mutants showed an increase in cell wall thickness with increased pbp2 gene expression. The VISA phenotype was not stable in D2P11 and showed a reduced autolysis profile. On the other hand, the mutant D23C9 differentiates from D2 and D2P11 in the autolysis profile, and pbp4 transcription profile. D2-derived mutants exhibited differences in the susceptibility to other antimicrobials. Our results highlight the possibility of selection of different VISA phenotypes from a single hVISA-ST100 genetic background.
    Mots-clés : ENVBAC, hVISA, MICROBIO, MRSA, ST100, Staphylococcus aureus, vancomycin, VISA.

  • T. Di Meo, W. Ghattas, C. Herrero, C. Velours, P. Minard, J. - P. Mahy, R. Ricoux, et A. Urvoas, « αRep A3: A versatile artificial scaffold for metalloenzyme design », Chemistry (Weinheim an Der Bergstrasse, Germany), 2017.
    Résumé : αRep is a new family of artificial proteins based on a thermostable alpha-helical repeated motif. One of its members, αRep A3, forms a stable homo-dimer with a wide cleft that is able to receive metal complexes and thus appears as suitable for generating new artificial biocatalysts. Based on the crystal structure of αRep A3, two positions (F119 and Y26) were chosen and changed independently into cysteine residues. A phenanthroline ligand was covalently attached to the unique cysteine of each protein variant and the corresponding biohybrids were purified and characterized. Once mutated and coupled to phenanthroline, the protein remained folded and dimeric. Copper(II) was bound specifically by the two biohybrids with two different binding modes and, in addition, the holo biohybrid A3F119NPH was found to be able to catalyze enantioselectively the Diels-Alder (D-A) cycloaddition with up to 62% ee. This study validates the choice of the αRep A3 dimer as a protein scaffold and provides a new promising route for the design and production of new enantioselective biohybrids based on entirely artificial proteins issued from a highly diverse library.
    Mots-clés : artificial repeat proteins, B3S, Diels-Alder reaction, Enantioselective Catalysis, MIP, PF, PIM.

  • S. A. Díaz, G. Lasarte Aragonés, S. Buckhout-White, X. Qiu, E. Oh, K. Susumu, J. S. Melinger, A. L. Huston, N. Hildebrandt, et I. L. Medintz, « Bridging Lanthanide to Quantum Dot Energy Transfer with a Short-Lifetime Organic Dye », The Journal of Physical Chemistry Letters, p. 2182-2188, 2017.
    Résumé : Semiconductor nanocrystals or quantum dots (QDs) should act as excellent Förster resonance energy transfer (FRET) acceptors due to their large absorption cross section, tunable emission, and high quantum yields. Engaging this type of FRET can be complicated due to direct excitation of the QD acceptor along with its longer excited-state lifetime. Many cases of QDs acting as energy transfer acceptors are within time-gated FRET from long-lifetime lanthanides, which allow the QDs to decay before observing FRET. Efficient QD sensitization requires the lanthanide to be in close proximity to the QD. To overcome the lifetime mismatch issues and limited transfer range, we utilized a Cy3 dye to bridge the energy transfer from an extremely long lived terbium emitter to the QD. We demonstrated that short-lifetime dyes can be used as energy transfer relays between extended lifetime components and in this way increased the distance of terbium-QD FRET to ∼14 nm.
    Mots-clés : B3S, NANO.

  • G. Dimchev, A. Steffen, F. Kage, V. Dimchev, J. Pernier, M. - F. Carlier, et K. Rottner, « Efficiency of lamellipodia protrusion is determined by the extent of cytosolic actin assembly », Molecular Biology of the Cell, p. mbc.E16-05-0334, mars 2017.

  • K. Djacem, P. Tavares, et L. Oliveira, « Bacteriophage SPP1 pac Cleavage: A Precise Cut without Sequence Specificity Requirement », Journal of Molecular Biology, 2017.
    Résumé : In many tailed bacteriophages, DNA packaging is initiated by recognition and cleavage of a specific sequence pac by the small (TerS) and large (TerL) terminase subunits. It was previously shown that the SPP1 pac region has two sequences where TerS binds (pacR and pacL), flanking the segment where TerL cleaves the SPP1 DNA (pacC). However, the pac-specific sequences required to achieve this endonucleolytic cut were not established. Their characterization is essential to understand the underlying mechanism. We show that the pacR sequence localized within 35bp downstream of the pac cut can be extensively degenerated, including its c1 and c2 repeats, and that only a disruption of a 5-bp polyadenine tract impairs the pac cleavage. This result together with deletion analysis of pacL shows that the specific DNA sequences required for targeting the terminase for pac cleavage are considerably shorter than the large region bound by TerS. Furthermore, extensive degeneration of the 6-bp target sequence within pacC where pac cleavage occurs reveals that TerL maintains, remarkably, its precise position of cleavage. Studies with SPP1-related phages show the conservation of the cut position, irrespective of the sequence variation in pacC and in pacR or the changes in pacL-pacC distance. Mechanistically, our data are compatible with a model in which TerS interactions with part of the pacL sequence and a poly-A tract in pacR are sufficient to orient very accurately the TerL nuclease to a defined pacC position. They also demonstrate that the resulting precise cut at pacC is independent of the targeted DNA sequence.
    Mots-clés : Bacteriophage, DNA packaging, genome recognition, pac cleavage, PHAG+, terminase, VIRO.

  • E. Dubois, N. Mathy, V. Régnier, J. Bischerour, C. Baudry, R. Trouslard, et M. Bétermier, « Multimerization properties of PiggyMac, a domesticated piggyBac transposase involved in programmed genome rearrangements », Nucleic Acids Research, 2017.
    Résumé : During sexual processes, the ciliate Paramecium eliminates 25-30% of germline DNA from its somatic genome. DNA elimination includes excision of ∼45 000 short, single-copy internal eliminated sequences (IESs) and depends upon PiggyMac (Pgm), a domesticated piggyBac transposase that is essential for DNA cleavage at IES ends. Pgm carries a core transposase region with a putative catalytic domain containing three conserved aspartic acids, and a downstream cysteine-rich (CR) domain. A C-terminal extension of unknown function is predicted to adopt a coiled-coil (CC) structure. To address the role of the three domains, we designed an in vivo complementation assay by expressing wild-type or mutant Pgm-GFP fusions in cells depleted for their endogenous Pgm. The DDD triad and the CR domain are essential for Pgm activity and mutations in either domain have a dominant-negative effect in wild-type cells. A mutant lacking the CC domain is partially active in the presence of limiting Pgm amounts, but inactive when Pgm is completely absent, suggesting that presence of the mutant protein increases the overall number of active complexes. We conclude that IES excision involves multiple Pgm subunits, of which at least a fraction must contain the CC domain.
    Mots-clés : DBG, DSMC, MICMAC.

  • S. Duigou et F. Boccard, « Long range chromosome organization in Escherichia coli: The position of the replication origin defines the non-structured regions and the Right and Left macrodomains », PLoS genetics, vol. 13, nᵒ 5, p. e1006758, 2017.
    Résumé : The Escherichia coli chromosome is organized into four macrodomains (Ori, Ter, Right and Left) and two non-structured regions. This organization influences the segregation of sister chromatids, the mobility of chromosomal DNA, and the cellular localization of the chromosome. The organization of the Ter and Ori macrodomains relies on two specific systems, MatP/matS for the Ter domain and MaoP/maoS for the Ori domain, respectively. Here by constructing strains with chromosome rearrangements to reshuffle the distribution of chromosomal segments, we reveal that the difference between the non-structured regions and the Right and Left lateral macrodomains relies on their position on the chromosome. A change in the genetic location of oriC generated either by an inversion within the Ori macrodomain or by the insertion of a second oriC modifies the position of Right and Left macrodomains, as the chromosome region the closest to oriC are always non-structured while the regions further away behave as macrodomain regardless of their DNA sequence. Using fluorescent microscopy we estimated that loci belonging to a non-structured region are significantly closer to the Ori MD than loci belonging to a lateral MD. Altogether, our results suggest that the origin of replication plays a prominent role in chromosome organization in E. coli, as it determines structuring and localization of macrodomains in growing cell.
    Mots-clés : DBG, OCB.

  • Y. Duroc, R. Kumar, L. Ranjha, C. Adam, R. Guérois, K. Md Muntaz, M. - C. Marsolier-Kergoat, F. Dingli, R. Laureau, D. Loew, B. Llorente, J. - B. Charbonnier, P. Cejka, et V. Borde, « Concerted action of the MutLβ heterodimer and Mer3 helicase regulates the global extent of meiotic gene conversion », eLife, vol. 6, janv. 2017.
    Mots-clés : AMIG, B3S, biochemistry, Chromosomes, genes, INTGEN, Meiosis, mismatch repair, Recombination, S. cerevisiae.

  • C. Eisenach et A. De Angeli, « Ion Transport at the Vacuole During Stomatal Movements », Plant Physiology, p. pp.00130.2017, avr. 2017.

  • N. El Bakkali-Tahéri, S. Tachon, M. Orio, S. Bertaina, M. Martinho, V. Robert, M. Réglier, T. Tron, P. Dorlet, et A. J. Simaan, « Characterization of Cu(II)-reconstituted ACC Oxidase using experimental and theoretical approaches », Archives of Biochemistry and Biophysics, 2017.
    Résumé : 1-Aminocyclopropane-1-carboxylic acid oxidase (ACCO) is a non heme iron(II) containing enzyme that catalyzes the final step of the ethylene biosynthesis in plants. The iron(II) ion is bound in a facial triad composed of two histidines and one aspartate (H177, D179 and H234). Several active site variants were generated to provide alternate binding motifs and the enzymes were reconstituted with copper(II). Continuous wave (cw) and pulsed Electron Paramagnetic Resonance (EPR) spectroscopies as well as Density Functional Theory (DFT) calculations were performed and models for the copper(II) binding sites were deduced. In all investigated enzymes, the copper ion is equatorially coordinated by the two histidine residues (H177 and H234) and probably two water molecules. The copper-containing enzymes are inactive, even when hydrogen peroxide is used in peroxide shunt approach. EPR experiments and DFT calculations were undertaken to investigate substrate's (ACC) binding on the copper ion and the results were used to rationalize the lack of copper-mediated activity.
    Mots-clés : ACC Oxidase, B3S, Copper, Density functional theory calculations, Electron paramagnetic resonance, Ethylene, LSOD.

  • R. El Helou, G. Pinna, O. Cabaud, J. Wicinski, R. Bhajun, L. Guyon, C. Rioualen, P. Finetti, A. Gros, B. Mari, P. Barbry, F. Bertucci, G. Bidaut, A. Harel-Bellan, D. Birnbaum, E. Charafe-Jauffret, et C. Ginestier, « miR-600 Acts as a Bimodal Switch that Regulates Breast Cancer Stem Cell Fate through WNT Signaling », Cell Reports, vol. 18, nᵒ 9, p. 2256-2268, 2017.

  • E. Errasti-Murugarren, A. Rodríguez-Banqueri, et J. L. Vázquez-Ibar, « Split GFP Complementation as Reporter of Membrane Protein Expression and Stability in E. coli: A Tool to Engineer Stability in a LAT Transporter », Methods in Molecular Biology (Clifton, N.J.), vol. 1586, p. 181-195, 2017.
    Résumé : Obtaining enough quantity of recombinant membrane transport proteins with optimal purity and stability for structural studies is a remarkable challenge. In this chapter, we describe a protocol to engineer SteT, the amino acid transporter of Bacillus subtilis, in order to improve its heterologous expression in Escherichia coli and its stability in detergent micelles. We built a library of 70 SteT mutants, combining a random mutagenesis protocol with a split GFP assay as reporter of protein folding and membrane insertion. Mutagenesis was restricted to residues situated in the transmembrane domains. Improved versions of SteT were successfully identified after analyzing the expression yield and monodispersity in detergent micelles of the library's members.
    Mots-clés : B3S, FSEC, Heterologous expression, LAT, LPSM, Membrane Transport Proteins, Split GFP, SteT.

  • C. Esnault, T. Dulermo, A. Smirnov, A. Askora, M. David, A. Deniset-Besseau, I. - B. Holland, et M. - J. Virolle, « Strong antibiotic production is correlated with highly active oxidative metabolism in Streptomyces coelicolor M145 », Scientific Reports, vol. 7, nᵒ 1, 2017.

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