Figure 7

Conceptual representation of the complex arsenite oxidation process in H. arsenicoxydans. Several major control mechanisms are involved: A. a transcriptional regulation: AoxS acts as a sensor of As(III) environmental signal and then phosphorylates AoxR. The phosphorylated AoxR binds to RpoN, which interacts with RNA polymerase. The RpoN-RNA polymerase complex with its AoxR co-activator initiates the aox operon transcription. DnaJ may regulate aox mRNA stability or act on the folding of AoxR or σ⁵⁴; B. Then, arsenite oxidase is synthesized and exported by the TAT secretion system; C. consequently, arsenite oxidase exerts a key role in arsenic detoxification, by the transformation of the more toxic form As(III) into a less toxic form As(V). This process is known to affect motility, which may involve a MCP chemotaxis protein and requires the DnaJ co-chaperone. IM= Inner Membrane, OM= Outer membrane.