Oligomeric behavior of the RND transporters CusA and AcrB in micellar solution of detergent

AbstractWe have used analytical ultracentrifugation to explore the oligomeric states of AcrB and CusA in micellar solution of detergent. These two proteins belong to the resistance, nodulation and cell division (RND) family of efflux proteins that are involved in multiple drug and heavy metal resistance. Only the structure of AcrB has been determined so far. Although functional RND proteins should assemble as trimers as AcrB does, both AcrB and CusA form a mixture of quaternary structures (from monomer to heavy oligomer) in detergent solution. The distribution of the oligomeric states was studied as a function of different parameters: nature and concentration of the detergent, ionic strength, pH, protein concentration. This pseudo-heterogeneity does not hamper the crystallization of AcrB as a homotrimer

Homéostasie et résistance au cuivre chez Cupriavidus metallidurans CH34 : la protéine CopH et les transporteurs membranaires CusA et CzcA

The copH gene is one of the 19 genes found in the cop cluster, involved in detoxification of copper from the cytoplasme as well as from the periplasm, in Cupriavidus metallidurans CH34, used as a model to study heavy metals resistance in bacteria. The function of CopH protein, located in the periplasm, is not clear yet, but its expression is induced by copper. We analysed the copper binding properties of CopH. The features are consistent with the presence of Cu(II) type 2 centers in a nitrogen ligand field. The only two histidine residus, ligands of copper as we thought, would not interact directly avec Cu(II) ions. The copper site would consist with 45 nitrogen atoms from the backbone of CopH. The study of membrane transporters CusA and CzcA has needed the optimised purification in detergents and the analysis of their behaviour in solution.Le gène copH est l'un des 19 gènes constituant le cluster cop, impliqué dans la détoxication du cuivre dans le cytoplasme et le périplasme, chez Cupriavidus metallidurans CH34, souche modèle pour l'étude de la résistance aux métaux lourds chez les bactéries. La protéine CopH, localisée dans le périplasme, possède une structure et une fonction inconnues mais son expression est stimulée par la présence de cuivre. Nous avons analysé les propriétés de liaison CopH-Cu : les données montrent la présence d'un centre Cu(II) de type 2 dans un champ de ligands azotés. Les 2 seuls résidus histidine, a priori ligands du cuivre, n'interagiraient pas directement avec les ions Cu(II). Le site cuivre serait constitué d'atomes d'azote appartenant à la chaîne principale de la protéine.L'étude des transporteurs CusA et CzcA a nécessité une purification optimisée en détergents et l'analyse de leur comportement en solution

Homéostasie et résistance au cuivre chez Cupriavidus metallidurans CH34 : la protéine CopH et les transporteurs membranaires CusA et CzcA

The copH gene is one of the 19 genes found in the cop cluster, involved in detoxification of copper from the cytoplasme as well as from the periplasm, in Cupriavidus metallidurans CH34, used as a model to study heavy metals resistance in bacteria. The function of CopH protein, located in the periplasm, is not clear yet, but its expression is induced by copper. We analysed the copper binding properties of CopH. The features are consistent with the presence of Cu(II) type 2 centers in a nitrogen ligand field. The only two histidine residus, ligands of copper as we thought, would not interact directly avec Cu(II) ions. The copper site would consist with 45 nitrogen atoms from the backbone of CopH. The study of membrane transporters CusA and CzcA has needed the optimised purification in detergents and the analysis of their behaviour in solution.Le gène copH est l'un des 19 gènes constituant le cluster cop, impliqué dans la détoxication du cuivre dans le cytoplasme et le périplasme, chez Cupriavidus metallidurans CH34, souche modèle pour l'étude de la résistance aux métaux lourds chez les bactéries. La protéine CopH, localisée dans le périplasme, possède une structure et une fonction inconnues mais son expression est stimulée par la présence de cuivre. Nous avons analysé les propriétés de liaison CopH-Cu : les données montrent la présence d'un centre Cu(II) de type 2 dans un champ de ligands azotés. Les 2 seuls résidus histidine, a priori ligands du cuivre, n'interagiraient pas directement avec les ions Cu(II). Le site cuivre serait constitué d'atomes d'azote appartenant à la chaîne principale de la protéine.L'étude des transporteurs CusA et CzcA a nécessité une purification optimisée en détergents et l'analyse de leur comportement en solution

copH from Cupriavidus metallidurans CH34. A novel perplasmic copper-Binding Protein

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Ancient genomes from present-day France unveil 7,000 years of its demographic history

International audienceGenomic studies conducted on ancient individuals across Europe have revealed how migrations have contributed to its present genetic landscape, but the territory of present-day France has yet to be connected to the broader European picture. We generated a large dataset comprising the complete mitochondrial genomes, Y chromosome markers and genotypes on a number of nuclear loci of interest of 243 individuals sampled across present-day France over a period spanning 7,000 years, complemented with a partially overlapping dataset of 58 low-coverage genomes. This panel provides a high-resolution transect of the dynamics of maternal and paternal lineages in France as well as of autosomal genotypes. Parental lineages and genomic data both revealed demographic patterns in France for the Neolithic and Bronze Age transitions consistent with neighboring regions, first with a migration wave of Anatolian farmers followed by varying degrees of admixture with autochthonous hunter-gatherers, then substantial gene flow from individuals deriving part of their ancestry from the Pontic Steppe at the onset of the Bronze Age. Our data have also highlighted the persistence of the Magdalenian-associated ancestry in hunter-gatherer populations outside of Spain and thus provide arguments for an expansion of these populations at the end of the Paleolithic period more northerly than what has been described so far. Finally, no major demographic changes were detected during the transition between the Bronze and Iron Ages