The gene arsR stems from the E. coli-specific plasmid R773 and
encodes for a transcriptional regulator with binding sites for
It is a repressor protein that binds to its promoter in the absence
of arsenic compounds therefore repressing the expression of
Arsenic compounds that are taken up by bacterial cells form a
complex with ArsR, thereby allosterically preventing the
association of ArsR with the promoter. Thus, the transcription of
downstream genes is induced.