The Escherichia coli Copper-responsivecopA Promoter Is Activated by Gold

Influence of Copper Resistance Determinants on Gold Transformation by Cupriavidus metallidurans Strain CH34

“…The cup determinant is under the control of the MerR-type regulator CupR (29), which acts as gold-sensing regulator similar to its homologs GolS in Salmonella and CueR in E. coli (14,15). MerRtype regulators are located on their operator as a repressor of the downstream operon and switch into an activator conformation upon metal binding.…”

“…First, the P IB1 -type ATPase GolT transports Au(I) from the cytoplasm to the periplasm. Although Escherichia coli CopA is a Cu(I) and Ag(I) transporter, but not an Au(I) transporter (15), Salmonella CopA might also recognize Au(I) as a substrate (13). GolB is a cytoplasmic gold chaperone, probably shuffling the metal substrate to either efflux ATPase.…”

Mechanisms of gold biomineralization in the bacterium Cupriavidus metallidurans

“…A study with E. coli demonstrated the nonspecific regulation of transcription by Au(III)-complexes; CueR, an MerR-like transcriptional activator that usually responds to Cu(II), was also activated by Au(III), and this activation was promoted by binding of Au to the cysteine (Cys) residues 112 and 120 (26). In C. metallidurans the Cys residues 112 and 120 also play a key role in the specific binding of Au(I)-complexes to the transcriptional activator CupR, which is involved in the defense against Au stress (27).…”

“…The cup/cop clusters contain genes encoding for sensor-, chaperone-, efflux-, cytochrome C-, and oxido-reductase proteins regulating the cyto-and periplasmic detoxification of Cu(I/II) (25). The DNAbinding transcriptional activator CupR (Rmet3525), an ortholog of CueR in Escherichia coli and GolS in S. enterica, the Cutransporting P-type ATPase CopA, as well as CopI, and the putative electron transferring cytochrome C-type copJ were strongly upregulated, suggesting their involvement in efflux and reduction of Au(III/I) to Au(0) (12,26,27). Experiments with C. metallidurans had demonstrated the induction of cupR with Au(I) (28).…”

“…A number of Cup/Cop proteins contain putative metal ligand residues such as cysteine (CupR, CopG) and methionine (e.g., CopKABCIJ), which might form thiolates-or thioethercomplexes with Au, respectively, as observed as Au(I)-S complexes by XANES (Fig. 3) (26). In addition, a number of methyltransferase genes (Rmet0529, 3846, 4140), were upregulated with Au(III) but not with other metals tested (Table S2) (28), and the C-bound Au observed at 100 M Au(III) may have been the result of Aumethylation.…”