US EPA

1936040 

Journal Article 

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

Slyemi, D; Moinier, D; Talla, E; Bonnefoy, V 

2013 

Yes 

Extremophiles
ISSN: 1431-0651
EISSN: 1433-4909 

17 

6 

911-920 

English 

23974983 

10.1007/s00792-013-0573-1 

WOS:000326046200003 

Thiomonas 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. 

Arsenic; Thiomonas; Arsenite oxidase; Cytochrome c; Metalloregulator; Gene regulation