排序方式: 共有59条查询结果,搜索用时 15 毫秒
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B Behrouzian L Fauconnot F Daligault C Nugier-Chauvin H Patin P H Buist 《European journal of biochemistry》2001,268(12):3545-3549
The hypothesis that the Delta9 desaturase of Chlorella vulgaris might operate by a synchronous mechanism has been tested using a kinetic isotope effect (KIE) approach. Thus the intermolecular primary deuterium KIE on the individual C-H bond cleavage steps involved in Delta9 desaturation have been determined by incubating growing cultures of C. vulgaris (strain 211/8K) with mixtures of the appropriate regiospecifically deuterated fatty acid analogues. Our analysis shows that the introduction of a double bond between C-9 and C-10 occurs in two discrete steps as the cleavage of the C9-H bond is very sensitive to isotopic substitution (kH/kD = 6.6 +/- 0.3) whereas a negligible isotope effect (kH/kD = 1.05 +/- 0.05) was observed for the C10-H bond-breaking step. Similar results were obtained for linoleic acid biosynthesis (Delta12 desaturation). These data clearly rule out a synchronous mechanism for these reactions. 相似文献
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Imen Ben-Mustapha Meriem Ben-Ali Najla Mekki Etienne Patin Christine Harmant Jihène Bouguila Houda Elloumi-Zghal Abdelaziz Harbi Mohamed Béjaoui Lamia Boughammoura Jalel Chemli Mohamed-Ridha Barbouche 《Immunogenetics》2014,66(1):67-71
Mendelian susceptibility to mycobacterial disease (MSMD) is a rare disorder predisposing apparently healthy individuals to infections caused by weakly virulent mycobacteria such as bacille Calmette–Guerin (BCG), environmental mycobacteria, and poorly virulent Salmonella strains. IL-12p40 deficiency is the first reported human disease due to a cytokine gene defect and is one of the deficiencies that cause MSMD. Nine mutant alleles only have been identified in the IL12B gene, and three of them are recurrent mutations due to a founder effect in specific populations. IL-12p40 deficiency has been identified especially in countries where consanguinity is high and where BCG vaccination at birth is universal. We investigated, in such settings, the clinical, cellular, and molecular features of six IL-12p40-deficient Tunisian patients having the same mutation in IL12B gene (c.298_305del). We found that this mutation is inherited as a common founder mutation arousing ~1,100 years ago. This finding facilitates the development of a preventive approach by genetic counseling and prenatal diagnosis especially in affected families. 相似文献
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N. V. Patin Z. A. Dietrich A. Stancil M. Quinan J. S. Beckler E. R. Hall J. Culter C. G. Smith M. Taillefert F. J. Stewart 《The ISME journal》2021,15(8):2206
Exploration of oxygen-depleted marine environments has consistently revealed novel microbial taxa and metabolic capabilities that expand our understanding of microbial evolution and ecology. Marine blue holes are shallow karst formations characterized by low oxygen and high organic matter content. They are logistically challenging to sample, and thus our understanding of their biogeochemistry and microbial ecology is limited. We present a metagenomic and geochemical characterization of Amberjack Hole on the Florida continental shelf (Gulf of Mexico). Dissolved oxygen became depleted at the hole’s rim (32 m water depth), remained low but detectable in an intermediate hypoxic zone (40–75 m), and then increased to a secondary peak before falling below detection in the bottom layer (80–110 m), concomitant with increases in nutrients, dissolved iron, and a series of sequentially more reduced sulfur species. Microbial communities in the bottom layer contained heretofore undocumented levels of the recently discovered phylum Woesearchaeota (up to 58% of the community), along with lineages in the bacterial Candidate Phyla Radiation (CPR). Thirty-one high-quality metagenome-assembled genomes (MAGs) showed extensive biochemical capabilities for sulfur and nitrogen cycling, as well as for resisting and respiring arsenic. One uncharacterized gene associated with a CPR lineage differentiated hypoxic from anoxic zone communities. Overall, microbial communities and geochemical profiles were stable across two sampling dates in the spring and fall of 2019. The blue hole habitat is a natural marine laboratory that provides opportunities for sampling taxa with under-characterized but potentially important roles in redox-stratified microbial processes.Subject terms: Metagenomics, Microbial ecology, Biogeochemistry 相似文献
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Arnould S Chames P Perez C Lacroix E Duclert A Epinat JC Stricher F Petit AS Patin A Guillier S Rolland S Prieto J Blanco FJ Bravo J Montoya G Serrano L Duchateau P Pâques F 《Journal of molecular biology》2006,355(3):443-458
The last decade has seen the emergence of a universal method for precise and efficient genome engineering. This method relies on the use of sequence-specific endonucleases such as homing endonucleases. The structures of several of these proteins are known, allowing for site-directed mutagenesis of residues essential for DNA binding. Here, we show that a semi-rational approach can be used to derive hundreds of novel proteins from I-CreI, a homing endonuclease from the LAGLIDADG family. These novel endonucleases display a wide range of cleavage patterns in yeast and mammalian cells that in most cases are highly specific and distinct from I-CreI. Second, rules for protein/DNA interaction can be inferred from statistical analysis. Third, novel endonucleases can be combined to create heterodimeric protein species, thereby greatly enhancing the number of potential targets. These results describe a straightforward approach for engineering novel endonucleases with tailored specificities, while preserving the activity and specificity of natural homing endonucleases, and thereby deliver new tools for genome engineering. 相似文献
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Fariza Ammam Djalal Meziane‐cherif Dominique Mengin‐Lecreulx Didier Blanot Delphine Patin Ivo G. Boneca Patrice Courvalin Thierry Lambert Thomas Candela 《Molecular microbiology》2013,89(4):612-625
vanGCd, a cryptic gene cluster highly homologous to the vanG gene cluster of Enterococcus faecalis is largely spread in Clostridium difficile. Since emergence of vancomycin resistance would have dramatic clinical consequences, we have evaluated the capacity of the vanGCd cluster to confer resistance. We showed that expression of vanGCd is inducible by vancomycin and that VanGCd, VanXYCd and VanTCd are functional, exhibiting D‐Ala : D‐Ser ligase, D,D‐dipeptidase and D‐Ser racemase activities respectively. In other bacteria, these enzymes are sufficient to promote vancomycin resistance. Trans‐complementation of C. difficile with the vanC resistance operon of Enterococcus gallinarum faintly impacted the MIC of vancomycin, but did not promote vancomycin resistance in C. difficile. Sublethal concentration of vancomycin led to production of UDP‐MurNAc‐pentapeptide[D‐Ser], suggesting that the vanGCd gene cluster is able to modify the peptidoglycan precursors. Our results indicated amidation of UDP‐MurNAc‐tetrapeptide, UDP‐MurNAc‐pentapeptide[D‐Ala] and UDP‐MurNAc‐pentapeptide[D‐Ser]. This modification is passed on the mature peptidoglycan where a muropeptide Tetra‐Tetra is amidated on the meso‐diaminopimelic acid. Taken together, our results suggest that the vanGCd gene cluster is functional and is prevented from promoting vancomycin resistance in C. difficile. 相似文献
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A Crequer C Picard E Patin A D'Amico A Abhyankar M Munzer M Debré SY Zhang G de Saint-Basile A Fischer L Abel G Orth JL Casanova E Jouanguy 《PloS one》2012,7(8):e44010
Epidermodysplasia verruciformis (EV) is characterized by persistent cutaneous lesions caused by a specific group of related human papillomavirus genotypes (EV-HPVs) in otherwise healthy individuals. Autosomal recessive (AR) EVER1 and EVER2 deficiencies account for two thirds of known cases of EV. AR RHOH deficiency has recently been described in two siblings with EV-HPV infections as well as other infectious and tumoral manifestations. We report here the whole-exome based discovery of AR MST1 deficiency in a 19-year-old patient with a T-cell deficiency associated with EV-HPV, bacterial and fungal infections. MST1 deficiency has recently been described in seven patients from three unrelated kindreds with profound T-cell deficiency and various viral and bacterial infections. The patient was also homozygous for a rare ERCC3 variation. Our findings broaden the clinical range of infections seen in MST1 deficiency and provide a new genetic etiology of susceptibility to EV-HPV infections. Together with the recent discovery of RHOH deficiency, they suggest that T cells are involved in the control of EV-HPVs, at least in some individuals. 相似文献
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Marjorie Levefaudes Delphine Patin Célia de Sousa-d'Auria Mohamed Chami Didier Blanot Mireille Hervé Michel Arthur Christine Houssin Dominique Mengin-Lecreulx 《The Journal of biological chemistry》2015,290(21):13079-13094
A gene named ltsA was earlier identified in Rhodococcus and Corynebacterium species while screening for mutations leading to increased cell susceptibility to lysozyme. The encoded protein belonged to a huge family of glutamine amidotransferases whose members catalyze amide nitrogen transfer from glutamine to various specific acceptor substrates. We here describe detailed physiological and biochemical investigations demonstrating the specific role of LtsA protein from Corynebacterium glutamicum (LtsACg) in the modification by amidation of cell wall peptidoglycan diaminopimelic acid (DAP) residues. A morphologically altered but viable ΔltsA mutant was generated, which displays a high susceptibility to lysozyme and β-lactam antibiotics. Analysis of its peptidoglycan structure revealed a total loss of DAP amidation, a modification that was found in 80% of DAP residues in the wild-type polymer. The cell peptidoglycan content and cross-linking were otherwise not modified in the mutant. Heterologous expression of LtsACg in Escherichia coli yielded a massive and toxic incorporation of amidated DAP into the peptidoglycan that ultimately led to cell lysis. In vitro assays confirmed the amidotransferase activity of LtsACg and showed that this enzyme used the peptidoglycan lipid intermediates I and II but not, or only marginally, the UDP-MurNAc pentapeptide nucleotide precursor as acceptor substrates. As is generally the case for glutamine amidotransferases, either glutamine or NH4+ could serve as the donor substrate for LtsACg. The enzyme did not amidate tripeptide- and tetrapeptide-truncated versions of lipid I, indicating a strict specificity for a pentapeptide chain length. 相似文献
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Etienne Patin Guillaume Laval Luis B. Barreiro Antonio Salas Ornella Semino Silvana Santachiara-Benerecetti Kenneth K. Kidd Judith R. Kidd Lolke Van der Veen Jean-Marie Hombert Antoine Gessain Alain Froment Serge Bahuchet Evelyne Heyer Lluís Quintana-Murci 《PLoS genetics》2009,5(4)
The transition from hunting and gathering to farming involved a major cultural innovation that has spread rapidly over most of the globe in the last ten millennia. In sub-Saharan Africa, hunter–gatherers have begun to shift toward an agriculture-based lifestyle over the last 5,000 years. Only a few populations still base their mode of subsistence on hunting and gathering. The Pygmies are considered to be the largest group of mobile hunter–gatherers of Africa. They dwell in equatorial rainforests and are characterized by their short mean stature. However, little is known about the chronology of the demographic events—size changes, population splits, and gene flow—ultimately giving rise to contemporary Pygmy (Western and Eastern) groups and neighboring agricultural populations. We studied the branching history of Pygmy hunter–gatherers and agricultural populations from Africa and estimated separation times and gene flow between these populations. We resequenced 24 independent noncoding regions across the genome, corresponding to a total of ~33 kb per individual, in 236 samples from seven Pygmy and five agricultural populations dispersed over the African continent. We used simulation-based inference to identify the historical model best fitting our data. The model identified included the early divergence of the ancestors of Pygmy hunter–gatherers and farming populations ~60,000 years ago, followed by a split of the Pygmies' ancestors into the Western and Eastern Pygmy groups ~20,000 years ago. Our findings increase knowledge of the history of the peopling of the African continent in a region lacking archaeological data. An appreciation of the demographic and adaptive history of African populations with different modes of subsistence should improve our understanding of the influence of human lifestyles on genome diversity. 相似文献