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| Peters, Judith; Martinez, Nicolas; Michoud, Gregoire; Carlo, Anais; Franzetti, Bruno; Oger, Philippe; Jebbar, Mohamed. |
| The majority of the biosphere is a high pressure environment. Around 70% of the marine biosphere lies at depths below 1000 m, i.e. at pressures of 100 bars or higher. To survive in these environments, deep-biosphere organisms have adapted to life at high pressure. In vitro studies showed that the activity of certain proteins originating from deep-sea organisms is less affected by high pressure than that of enzymes from surface organisms [1-3]. However, the genetic and structural bases for this increased pressure resistance are still unknown. Elastic incoherent neutron scattering studies, which provide access to information about molecular dynamics, constitute a very promising approach to decipher the structural adaptation in proteins living under high... |
| Tipo: Text |
Palavras-chave: Neutron Scattering; Molecular Dynamics; High Pressure; Deep Sea Microbes. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00251/36186/34725.pdf |
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| Thiel, Axel; Michoud, Gregoire; Moalic, Yann; Flament, Didier; Jebbar, Mohamed. |
| In this study, we developed a gene disruption system for Thermococcus barophilus using simvastatin for positive selection and 5-fluoroorotic acid (5-FOA) for negative selection or counterselection to obtain markerless deletion mutants using single-and double-crossover events. Disruption plasmids carrying flanking regions of each targeted gene were constructed and introduced by transformation into wild-type T. barophilus MP cells. Initially, a pyrF deletion mutant was obtained as a starting point for the construction of further markerless mutants. A deletion of the hisB gene was also constructed in the UBOCC-3256 (Delta pyrF) background, generating a strain (UBOCC-3260) that was auxotrophic for histidine. A functional pyrF or hisB allele from T. barophilus... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00187/29818/28263.pdf |
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| Michoud, Gregoire; Jebbar, Mohamed. |
| Pyrococcus yayanosii CH1, as the first and only obligate piezophilic hyperthermophilic microorganism discovered to date, extends the physical and chemical limits of life on Earth. It was isolated from the Ashadze hydrothermal vent at 4,100 m depth. Multi-omics analyses were performed to study the mechanisms used by the cell to cope with high hydrostatic pressure variations. In silico analyses showed that the P. yayanosii genome is highly adapted to its harsh environment, with a loss of aromatic amino acid biosynthesis pathways and the high constitutive expression of the energy metabolism compared with other non-obligate piezophilic Pyrococcus species. Differential proteomics and transcriptomics analyses identified key hydrostatic pressure-responsive genes... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00342/45295/44756.pdf |
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| Martinez, N.; Michoud, Gregoire; Cario, A.; Ollivier, J.; Franzetti, B.; Jebbar, Mohamed; Oger, P.; Peters, J.. |
| Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00350/46083/45742.pdf |
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| Lossouarn, Julien; Nesbo, Camilla L.; Mercier, Coraline; Zhaxybayeva, Olga; Johnson, Milo S.; Charchuck, Rhianna; Farasin, Julien; Bienvenu, Nadege; Baudoux, Anne-claire; Michoud, Gregoire; Jebbar, Mohamed; Geslin, Claire. |
| Prokaryotic viruses play a major role in the microbial ecology and evolution. However, the virosphere associated with deep-sea hydrothermal ecosystems remains largely unexplored. Numerous instances of lateral gene transfer have contributed to the complex and incongruent evolutionary history of Thermotogales, an order well represented in deep-sea hydrothermal vents. The presence of clustered regularly interspaced short palindromic repeats (CRISPR) loci has been reported in all Thermotogales genomes, suggesting that these bacteria have been exposed to viral infections that could have mediated gene exchange. In this study, we isolated and characterized the first virus infecting bacteria from the order Thermotogales, Marinitoga piezophila virus 1 (MPV1). The... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00254/36483/36732.pdf |
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| Golub, Maksym; Martinez, Nicolas; Michoud, Gregoire; Ollivier, Jacques; Jebbar, Mohamed; Oger, Philippe; Peters, Judith. |
| In live cells, high concentrations up to 300–400 mg/mL, as in Eschericia coli (Ellis, R. J. Curr. Opin. Struct. Biol. 2001, 11, 114) are achieved which have effects on their proper functioning. However, in many experiments only individual parts of the cells as proteins or membranes are studied in order to get insight into these specific components and to avoid the high complexity of whole cells, neglecting by the way the influence of crowding. In the present study, we investigated cells of the order of Thermococcales, which are known to live under extreme conditions, in their intact form and after cell lysis to extract the effect of crowding on the molecular dynamics of the proteome and of water molecules. We found that some parameters characterizing the... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00454/56526/58329.pdf |
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