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| Registros recuperados: 38 | |
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| Santana,Priscila Bessa; Ghilardi Junior,Rubens; Alves,Claudio Nahum; Silva,Jeronimo Lameira; McCulloch,John Anthony; Schneider,Maria Paula Cruz; Silva,Artur da Costa da. |
| Methanogenic archaeans are organisms of considerable ecological and biotechnological interest that produce methane through a restricted metabolic pathway, which culminates in the reaction catalyzed by the Methyl-coenzyme M reductase (Mcr) enzyme, and results in the release of methane. Using a metagenomic approach, the gene of the a subunit of mcr (mcrα) was isolated from sediment sample from an anoxic zone, rich in decomposing organic material, obtained from the Tucuruí hydroelectric dam reservoir in eastern Brazilian Amazonia. The partial nucleotide sequences obtained were 83 to 95% similar to those available in databases, indicating a low diversity of archaeans in the reservoir. Two orders were identified -the Methanomicrobiales, and a unique Operational... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amazonian; Archaea; Diversity; Methyl-coenzyme M reductase; Mcrα; Homology modeling. |
| Ano: 2012 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572012000100018 |
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| Hogrel, Gaelle; Lu, Yang; Alexandre, Nicolas; Bossé, Audrey; Dulermo, Remi; Ishino, Sonoko; Ishino, Yoshizumi; Flament, Didier. |
| Among the three domains of life, the process of homologous recombination (HR) plays a central role in the repair of double-strand DNA breaks and the restart of stalled replication forks. Curiously, main protein actors involved in the HR process appear to be essential for hyperthermophilic Archaea raising interesting questions about the role of HR in replication and repair strategies of those Archaea living in extreme conditions. One key actor of this process is the recombinase RadA, which allows the homologous strand search and provides a DNA substrate required for following DNA synthesis and restoring genetic information. DNA polymerase operation after the strand exchange step is unclear in Archaea. Working with Pyrococcus abyssi proteins, here we show... |
| Tipo: Text |
Palavras-chave: Homologous recombination; Archaea; DNA polymerase; Recombinase; DNA repair. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00641/75274/75539.pdf |
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| Oger, Philippe M.; Jebbar, Mohamed. |
| The current paper reviews strategies employed by microorganisms from the deep biosphere, especially piezophiles (from the greek piezo = to press and philo = love), to cope with high hydrostatic pressure (HHP) prevailing in these biotopes. The aim of this review is not to constitute an exhaustive report of our current knowledge on the physiology of piezophiles, as recent reviews have covered part of this subject in detail (Abe, 2007; Lauro and Bartlett, 2008; Michiels et al., 2008; Simonato et al., 2006). Rather, we illustrate here, via a few chosen examples, where we stand in our understanding of the mechanisms employed by microorganisms from the depths of our planet to cope with HHP. (C) 2010 Institut Pasteur. Published by Elsevier Masson SAS. All rights... |
| Tipo: Text |
Palavras-chave: Adaptation and evolution; Archaea; Deep biosphere; High hydrostatic pressure; Piezophile; Stress response. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00027/13797/11043.pdf |
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| Rouillon, Christophe; Henneke, Ghislaine; Flament, Didier; Querellou, Joel; Raffin, Jean-paul. |
| DNA replication in Archaea, as in other organisms, involves large protein complexes called replisomes. In the Euryarchaeota subdomain, only two putative replicases have been identified, and their roles in leading and lagging strand DNA synthesis are still poorly understood. In this study, we focused on the coupling of proliferating cell nuclear antigen (PCNA)loading mechanisms with DNA polymerase function in the Euryarchaea Pyrococcus abyssi. PCNA spontaneously loaded onto primed DNA, and replication factor C dramatically increased this loading. Surprisingly, the family B DNA polymerase (Pol B) also increased PCNA loading, probably by stabilizing the clamp on primed DNA via an essential motif. In contrast, on an RNA-primed DNA template, the PCNA/Pol B... |
| Tipo: Text |
Palavras-chave: RF C; PCNA loading; DNA polymerase switching; DNA replication; Archaea. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2638.pdf |
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| Castrec, Benoit. |
| DNA replication is a functionally conserved mechanism among the three domains of life. This processus is performed by DNA polymerases with two accessories factors, PCNA and RF-C, sliding clamp and clamp loader, respectively. Our model of study, the Euryarchaeota Pyrococcus abyssi, possesses one monomeric DNA polymerase, belonging to the Family B, and one heterodimeric DNA polymerase, belonging to the Family D. Usually, proteins interact with PCNA at a hydrophobic pocket which is formed by the IDCL (interdomain connecting loop) and the C-terminus. These interactions are mediated through common motifs like the PIP box (motif PCNA interacting Protein). We have demonstrated that Pol B has just one PIP box motif at the C-terminus, while Pol D has two PIP-type... |
| Tipo: Text |
Palavras-chave: Thermostability; Interactions; Motifs; DNA replication; RF C; PCNA; DNA polymerases; Archaea; Thermostabilité; Interactions; Motifs; Réplication de l'ADN; RF C; PCNA; ADN polymérases; Archaea. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/these-6940.pdf |
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| Castrec, Benoit; Rouillon, Christophe; Henneke, Ghislaine; Flament, Didier; Querellou, Joel; Raffin, Jean-paul. |
| Replicative DNA polymerases possess a canonical C-terminal proliferating cell nuclear antigen (PCNA)-binding motif termed the PCNA-interacting protein (PIP) box. We investigated the role of the PIP box on the functional interactions of the two DNA polymerases, PabPol B (family B) and PabPol D (family D), from the hyperthermophilic euryarchaeon Pyrococcus abyssi, with its cognate PCNA. The PIP box was essential for interactions of PabPol B with PCNA, as shown by surface plasmon resonance and primer extension studies. In contrast, binding of PabPol D to PCNA was affected only partially by removing the PIP motif. We identified a second palindromic PIP box motif at the N-terminus of the large subunit of PabPol D that was required for the interactions of PabPol... |
| Tipo: Text |
Palavras-chave: Archaea; PIP box; PCNA binding motifs; DNA polymerases; DNA replication. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-7317.pdf |
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| Killelea, Tom; Ralec, Celine; Bosse, Audrey; Henneke, Ghislaine. |
| DNA polymerases are versatile tools used in numerous important molecular biological core technologies like the ubiquitous polymerase chain reaction (PCR), cDNA cloning, genome sequencing, and nucleic acid based diagnostics. Taking into account the multiple DNA amplification techniques in use, different DNA polymerases must be optimized for each type of application. One of the current tendencies is to reengineer or to discover new DNA polymerases with increased performance and broadened substrate spectra. At present, there is a great demand for such enzymes in applications, e.g., forensics or paleogenomics. Current major limitations hinge on the inability of conventional PCR enzymes, such as Taq, to amplify degraded or low amounts of template DNA. Besides,... |
| Tipo: Text |
Palavras-chave: DNA polymerase; Archaea; Family D; PCR; Pyrococcus. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00193/30450/28871.pdf |
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| Lemor, Melanie; Kong, Ziqing; Henry, Etienne; Brizard, Raphael; Laurent, Sebastien; Bosse, Audrey; Henneke, Ghislaine. |
| Consistent with the fact that ribonucleotides (rNTPs) are in excess over deoxyribonucleotides (dNTPs) in vivo, recent findings indicate that replicative DNA polymerases (DNA Pols) are able to insert ribonucleotides (rNMPs) during DNA synthesis, raising crucial questions about the fidelity of DNA replication in both Bacteria and Eukarya. Here, we report that the level of rNTPs is 20-fold higher than that of dNTPs in Pyrococcus abyssi cells. Using dNTP and rNTP concentrations present in vivo, we recorded rNMP incorporation in a template-specific manner during in vitro synthesis, with the family-D DNA Pol (PolD) having the highest propensity compared with the family-B DNA Pol and the p41/p46 complex. We also showed that ribonucleotides accumulate at a... |
| Tipo: Text |
Palavras-chave: Archaea; DNA replication and repair; DNA polymerase; Nucleotide pool; Translesion synthesis. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00464/57603/59796.pdf |
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| Henneke, Ghislaine; Raffin, Jean-paul; Ferrari, Elena; Jonsson, Zophonías; Dietrich, Jacques; Hubscher, Ulrich. |
| We have cloned the gene encoding proliferating cell nuclear antigen (PCNA) from the hyperthermophilic euryarchaeote Thermococcus fumicolans (Tfu). Tfu PCNA contains 250 amino acids with a calculated M-r of 28,000 and is 26% identical to human PCNA. Next, Tfu PCNA was overexpressed in Escherichia coli and it showed an apparent molecular mass of 33.5 kDa. The purified Tfu PCNA was tested first with recombinant Tfu DNA polymerase I (Tfu pol) and second with calf thymus DNA polymerase delta (pol delta). When tested with the homologous Tfu pol on bacteriophage lambda DNA, large amounts of Tfu PCNA were required to obtain two- to threefold stimulation. Surprisingly, however, Tfu PCNA was much more efficient than human PCNA in stimulating calf thymus pol delta.... |
| Tipo: Text |
Palavras-chave: DNA polymerase delta; Conservation; Thermococcus fumicolans; Archaea; Hyperthermophile; PCNA. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/2000/publication-659.pdf |
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| Roussel, Erwan; Sauvadet, Anne Laure; Allard, Jonathan; Chaduteau, Carine; Richard, Pierre; Cambon Bonavita, Marie-anne; Chaumillon, Eric. |
| In Marennes-Oleron Bay, a macro-tidal bay located on the French Atlantic coast, kilometer-scale acoustic turbidity reveals an accumulation of free gas in the sediment. Large concentrations of organic matter and rapid sedimentation rates provide ideal settings for biogenic methane cycling. We integrate seismic, sedimentologic, biogeochemical and molecular genetic approaches to determine whether microbial methane cycling is involved in this process. Here we show that the acoustic turbidity upper boundary matched with X-ray facies displaying fissures with the highest methane concentrations, demonstrating the existence of methane bubbles in the sediment. 16S rRNA and mcrA gene clone libraries were dominated by sequences affiliated to the three known ANME... |
| Tipo: Text |
Palavras-chave: Sediment; Methane; McrA; 16S rRNA; Archaea. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6165.pdf |
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| Durbin, Alan M.; Teske, Andreas. |
| Examining the patterns of archaeal diversity in little-explored organic-lean marine subsurface sediments presents an opportunity to study the association of phylogenetic affiliation and habitat preference in uncultured marine Archaea. Here we have compiled and re-analyzed published archaeal 16S rRNA clone library datasets across a spectrum of sediment trophic states characterized by a wide range of terminal electron-accepting processes. Our results show that organic-lean marine sediments in deep marine basins and oligotrophic open ocean locations are inhabited by distinct lineages of archaea that are not found in the more frequently studied, organic-rich continental margin sediments. We hypothesize that different combinations of electron donor and acceptor... |
| Tipo: Text |
Palavras-chave: Archaea; Marine sediments; Oligotrophy; Subsurface; Phylogeny; Uncultured archaea. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00263/37444/35695.pdf |
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| Collos, Yves; Hadjadji, Imene; Plisson, Benoit; Cecchi, Philippe; Laabir, Mohamed; Bechemin, Christian; Masseret, Estelle. |
| Alexandrium tamarense (M. Lebour) Balech strains isolated in spring 2007 from a single bloom in Thau lagoon have been grown in nonaxenic artificial media. For three strains showing large oscillations in biomass (crashes followed by recoveries) on a scale of several days, a significant relationship was observed between changes in cell densities (as in vivo fluorescence) and changes in nitrate concentrations. Increases in cell densities were accompanied by decreases in nitrate, while decreases in cell densities corresponded to increases in nitrate, presumably due to nitrification. Net increases in nitrate could reach up to 15 mu mol N . L(-1) . d(-1) indicating a very active nitrifying archaeal/bacterial population. However, following population crashes,... |
| Tipo: Text |
Palavras-chave: Alexandrium tamarense; Archaea; Bacteria; Decay; Growth; Nitrate; Nitrification; Oscillations. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00049/16046/13585.pdf |
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| Lazar, Cassandre; Parkes, R. John; Cragg, Barry A.; L'Haridon, Stephane; Toffin, Laurent. |
| Marine mud volcanoes are geological structures emitting large amounts of methane from their active centres. The Amsterdam mud volcano (AMV), located in the Anaximander Mountains south of Turkey, is characterized by intense active methane seepage produced in part by methanogens. To date, information about the diversity or the metabolic pathways used by the methanogens in active centres of marine mud volcanoes is limited. 14C-radiotracer measurements showed that methylamines/methanol, H2/CO2 and acetate were used for methanogenesis in the AMV. Methylotrophic methanogenesis was measured all along the sediment core, Methanosarcinales affiliated sequences were detected using archaeal 16S PCR-DGGE and mcrA gene libraries, and enrichments of methanogens showed... |
| Tipo: Text |
Palavras-chave: Methanogenesis; McrA; Archaea. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00087/19795/17538.pdf |
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| Roussel, Erwan; Konn, Cecile; Charlou, Jean-luc; Donval, Jean-pierre; Fouquet, Yves; Querellou, Joel; Prieur, Daniel; Cambon-bonavita, Marie-anne. |
| The distribution of Archaea and methanogenic, methanotrophic and sulfate-reducing communities in three Atlantic ultramafic-hosted hydrothermal systems (Rainbow, Ashadze, Lost City) was compared using 16S rRNA gene and functional gene (mcrA, pmoA and dsrA) clone libraries. The overall archaeal community was diverse and heterogeneously distributed between the hydrothermal sites and the types of samples analyzed (seawater, hydrothermal fluid, chimney and sediment). The Lost City hydrothermal field, characterized by high alkaline warm fluids (pH>11; T<95 °C), harbored a singular archaeal diversity mostly composed of unaffiliated Methanosarcinales. The archaeal communities associated with the recently discovered Ashadze 1 site, one of the deepest active... |
| Tipo: Text |
Palavras-chave: Archaea; Hydrothermal vent; Mid-Atlantic Ridge; 16S rRNA gene; Sediment; Ultramafic. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00067/17836/15573.pdf |
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| Gonthier, Isabelle; Rager, Marie-noëlle; Metzger, Pierre; Guezennec, Jean; Largeau, Claude. |
| The lipids of a deep-sea hydrothermal vent arch ae on, Thermococcus S 557, were isolated, purified and structurally determined. Based on acid methanolysis and spectroscopic studies, the polar lipids were shown to comprise diphytanyl glycerol and dibiphytanyl diglycerol, typical membrane lipids of Arch aea. From the neutral lipids, 2,3-di-O-dihydro-14,15-geranylgeranyl glycerol was isolated. This novel ether lipid is, very likely, a close intermediate in the biosynthesis of diphytanyl glycerol diether in Arch aea. |
| Tipo: Text |
Palavras-chave: Mass spectrometry; NMR; Novel glycerol diether lipid; Thermococcus sp; Archaea. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-736.pdf |
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| Le Breton, Magali; Henneke, Ghislaine; Norais, C; Flament, Didier; Myllykallio, H; Querellou, Joel; Raffin, Jean-paul. |
| We report on the characterization of the DNA primase complex of the hyperthermophilic archaeon Pyrococcus abyssi (Pab). The Pab DNA primase complex is composed of the proteins Pabp41 and Pabp46, which show sequence similarities to the p49 and p58 subunits, respectively, of the eukaryotic polymerase alpha-primase complex. Both subunits were expressed, purified, and characterized. The Pabp41 subunit alone had no RNA synthesis activity but could synthesize long (up to 3 kb) DNA strands. Addition of the Pabp46 subunit increased the rate of DNA synthesis but decreased the length of the DNA fragments synthesized and conferred RNA synthesis capability. Moreover, in our experimental conditions, Pab DNA primase had comparable affinities for ribonucleotides and... |
| Tipo: Text |
Palavras-chave: Strand displacement; Gap filling; DNA primase; Archaea; DNA replication. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3520.pdf |
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| Registros recuperados: 38 | |
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