Characterisation of CadR from Pseudomonas aeruginosa:: a Cd(II)-responsive MerR homologue

cadR from Pseudomonas aeruginosa encodes a transcriptional regulatory protein which responds to Cd(II)much greater thanZn(II)>Hg(II) at its cognate promoter P-cadA.(.) CadR will also act to induce transcription at the Escherichia coli ZntR cognate promoter, P-zntA however, the induction profile is altered to Hg(II)>Cd(II)>Zn(II). Two separate single base pair deletions within P-zntA result in further alteration of relative specificity in metal-ion induction profile for CadR. This demonstrates that the operator\promoter sequence can play a role in defining optimal ligand response and that for these regulators specificity is not solely a function of the regulatory protein. (C) 2003 Elsevier Inc. All rights reserved.