Structure, Function, and Evolution of the Thiomonas spp. Genome

Bacteria of the Thiomonas genus are ubiquitous in extreme environments, such as arsenic-rich acid mine drainage (AMD). The genome of one of these strains, Thiomonas sp. 3As, was sequenced, annotated, and examined, revealing specific adaptations allowing this bacterium to survive and grow in its highly toxic environment. In order to explore genomic diversity as well as genetic evolution in Thiomonas spp., a comparative genomic hybridization (CGH) approach was used on eight different strains of the Thiomonas genus, including five strains of the same species. Our results suggest that the Thiomonas genome has evolved through the gain or loss of genomic islands and that this evolution is influenced by the specific environmental conditions in which the strains live

Characterization of "thiomonas arsenitoxydans" and study of th regulation of genes encoding the arsenite oxidase

Thiomonas sp. 3As, bactérie isolée d'eaux de drainage de mine (Carnoulès, France) contaminées par l'arsenic, a la capacité d'oxyder l'arsenic. Nous l'avons caractérisée aux niveaux physiologique et chimiotaxonomique, ce qui a montré qu'il s'agit d'une nouvelle espèce : "Thiomonas arsenitoxudans". L'arsénite axydase catalyse l'oxydation de l'arsénite (As(III)) en arséniate (As(V)), moins soluble et toxique. Nous avons montré chez cette bactérie que les gènes aoxAB codant pour les 2 sous-unités de cette enzyme sont co-transcrits ArsR/SmtB. Cet opéron est transcrit en présence d'As(III) et d'As(V). Nos résultats indiquent qu'ArsR-like (1) est stabilisé par l'As(III) ou l'As(V). Nos résultats suggèrent qu'ArsR-like a un mécanisme d'action différent de celui établi pour les autres membres de la famille ArsR/SmtBThiamonas sp. 3As, a bacterium isolated from acid mine drainage waters heavily loaded with arsenic (Carnoulès, France), has the capacity to oxidize arsenic. We characterized it both at the physiological and chemotaxonomical levels, which showed that it belongs to a new species : "thiomonas arsenitoxydans". The arsenite oxidase catalyses the oxidation of arsenite (As(III)) to arsenate (As(V)), less soluble and toxic. We showed that the genes aoxAB encoding the 2 sub-units of this enzyme are co-transcribed with the genes coding for 2 cytochromes c and a metalloregulator ArsR-like of the ArsR/SmtB family in "Tm. arsenitoxydans". This operon is transcribed in the presence of As(III)) or As(V). Our results indicaded that ArsR-like (1) is stabilized by As(III) or As(V), and (2) binds on the regulatory sequence of the aox operon in the presence of As(III) or As(V). From oour results, we suggest that the mechanism of ArsR-like is different from that of the other members of the ArsR/SmtB family

Caractérisation de "Thiomonas arsenitoxydans" et étude de la régulation des gènes codant pour l'arsénite oxydase

Thiomonas sp. 3As, bactérie isolée d'eaux de drainage de mine (Carnoulès, France) contaminées par l'arsenic, a la capacité d'oxyder l'arsenic. Nous l'avons caractérisée aux niveaux physiologique et chimiotaxonomique, ce qui a montré qu'il s'agit d'une nouvelle espèce : "Thiomonas arsenitoxudans". L'arsénite axydase catalyse l'oxydation de l'arsénite (As(III)) en arséniate (As(V)), moins soluble et toxique. Nous avons montré chez cette bactérie que les gènes aoxAB codant pour les 2 sous-unités de cette enzyme sont co-transcrits ArsR/SmtB. Cet opéron est transcrit en présence d'As(III) et d'As(V). Nos résultats indiquent qu'ArsR-like (1) est stabilisé par l'As(III) ou l'As(V). Nos résultats suggèrent qu'ArsR-like a un mécanisme d'action différent de celui établi pour les autres membres de la famille ArsR/SmtBThiamonas sp. 3As, a bacterium isolated from acid mine drainage waters heavily loaded with arsenic (Carnoulès, France), has the capacity to oxidize arsenic. We characterized it both at the physiological and chemotaxonomical levels, which showed that it belongs to a new species : "thiomonas arsenitoxydans". The arsenite oxidase catalyses the oxidation of arsenite (As(III)) to arsenate (As(V)), less soluble and toxic. We showed that the genes aoxAB encoding the 2 sub-units of this enzyme are co-transcribed with the genes coding for 2 cytochromes c and a metalloregulator ArsR-like of the ArsR/SmtB family in "Tm. arsenitoxydans". This operon is transcribed in the presence of As(III)) or As(V). Our results indicaded that ArsR-like (1) is stabilized by As(III) or As(V), and (2) binds on the regulatory sequence of the aox operon in the presence of As(III) or As(V). From oour results, we suggest that the mechanism of ArsR-like is different from that of the other members of the ArsR/SmtB familyAIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

Characterization of "thiomonas arsenitoxydans" and study of th regulation of genes encoding the arsenite oxidase

Thiomonas sp. 3As, bactérie isolée d'eaux de drainage de mine (Carnoulès, France) contaminées par l'arsenic, a la capacité d'oxyder l'arsenic. Nous l'avons caractérisée aux niveaux physiologique et chimiotaxonomique, ce qui a montré qu'il s'agit d'une nouvelle espèce : "Thiomonas arsenitoxudans". L'arsénite axydase catalyse l'oxydation de l'arsénite (As(III)) en arséniate (As(V)), moins soluble et toxique. Nous avons montré chez cette bactérie que les gènes aoxAB codant pour les 2 sous-unités de cette enzyme sont co-transcrits ArsR/SmtB. Cet opéron est transcrit en présence d'As(III) et d'As(V). Nos résultats indiquent qu'ArsR-like (1) est stabilisé par l'As(III) ou l'As(V). Nos résultats suggèrent qu'ArsR-like a un mécanisme d'action différent de celui établi pour les autres membres de la famille ArsR/SmtBThiamonas sp. 3As, a bacterium isolated from acid mine drainage waters heavily loaded with arsenic (Carnoulès, France), has the capacity to oxidize arsenic. We characterized it both at the physiological and chemotaxonomical levels, which showed that it belongs to a new species : "thiomonas arsenitoxydans". The arsenite oxidase catalyses the oxidation of arsenite (As(III)) to arsenate (As(V)), less soluble and toxic. We showed that the genes aoxAB encoding the 2 sub-units of this enzyme are co-transcribed with the genes coding for 2 cytochromes c and a metalloregulator ArsR-like of the ArsR/SmtB family in "Tm. arsenitoxydans". This operon is transcribed in the presence of As(III)) or As(V). Our results indicaded that ArsR-like (1) is stabilized by As(III) or As(V), and (2) binds on the regulatory sequence of the aox operon in the presence of As(III) or As(V). From oour results, we suggest that the mechanism of ArsR-like is different from that of the other members of the ArsR/SmtB family.AIX-MARSEILLE2-Bib.electronique (130559901) / SudocSudocFranceF

Organization and regulation of the arsenite oxidase operon of the moderately acidophilic and facultative chemoautotrophic Thiomonas arsenitoxydans

A utilisé MicroScope PlatformInternational audienceThiomonas arsenitoxydans is an acidophilic and facultatively autotrophic bacterium that can grow by oxidizing arsenite to arsenate. A comparative genomic analysis showed that the T. arsenitoxydans aioBA cluster encoding the two subunits of arsenite oxidase is distinct from the other clusters, with two specific genes encoding a cytochrome c and a metalloregulator belonging to the ArsR/SmtB family. These genes are cotranscribed with aioBA, suggesting that these cytochromes c are involved in arsenite oxidation and that this operon is controlled by the metalloregulator. The growth of T. arsenitoxydans in the presence of thiosulfate and arsenite, or arsenate, is biphasic. Real-time PCR experiments showed that the operon is transcribed during the second growth phase in the presence of arsenite or arsenate, whereas antimonite had no effect. These results suggest that the expression of the aioBA operon of T. arsenitoxydans is regulated by the electron donor present in the medium, i.e., is induced in the presence of arsenic but is repressed by more energetic substrates. Our data indicate that the genetic organization and regulation of the aioBA operon of T. arsenitoxydans differ from those of the other arsenite oxidizers