ZntR is a Zn(II)-responsive MerR-like transcriptional regulator of zntA inEscherichia coli

We have identified the promoter/operator region of the zntA gene of Escheri chia coil and shown that Zn(II) is the primary inducer of expression of thi s Zn(II)/Cd(II) export gene. The promoter PzntA shows sequence similarities to the promoters of mercury resistance (mer) operons, including a long spa cer region containing an inverted repeat sequence. The gene encoding the tr anscriptional regulator of PzntA, designated zntR, has been identified from genome sequence data, by expression of the gene product and by insertional inactivation/complementation. The ZntR product is a member of the MerR fam ily of transcriptional regulators and appears to act as a hypersensitive tr anscriptional switch. A hybrid MerR/ZntR protein has been constructed and i ndicates that the C-terminal region of ZntR recognizes Zn(II).