Effects of Arsenite Resistance on the Growth and Functional Gene Expression of Leptospirillum ferriphilum and Acidithiobacillus thiooxidans in Pure Culture and Coculture

Figure 8

Schematic representation of arsenic interaction with ars operon in L. ferriphilum YSK and At. thiooxidans A01 based on documented models [1, 11, 16, 17, 42, 48–55] and bioinformatics analysis of draft genome sequence. ArsR is an As(III)-responsive transcriptional repressor that binds to the ars promoter, repressing transcription. Binding of arsenite to ArsR results in dissociation of the repressor from the DNA and hence gene expression. Arsenate is reduced to arsenite by ArsC. ArsRC also have the function of ArsR and ArsC. Intracellular arsenite is extruded from the cells by ArsB. ArsH is considered to be a H₂O₂-forming NADPH-FMN oxidoreductase that might produce hydrogen peroxide which may contribute to the conversion of arsenate to arsenite and played a role in the response to oxidative stress The unknown protein named ArsU was associated with arsenic resistance.