title: Control of copper homeostasis in Escherichia coli by a P-type ATPase, CopA, and a MerR-like transcriptional activator, CopR.
abstract: We have isolated and characterized a copper sensitive Escherichia coli mutant that is deficient in the copper transporting P-type ATPase encoded by the copA gene (previously ybaR). Measurements of uptake and efflux of 64Cu by wild-type and mutant cells implicated the CopA protein in copper efflux from the cytoplasm, and further demonstrated that cell-associated copper in intact E. coli cells is distributed between two kinetically distinguishable pools, the ratio of which was dramatically disturbed by the copA mutation. Using a copA-lacZ gene fusion the copA promoter was found to be specifically induced by copper, and this induction was shown to be dependent on a MerR-like transcriptional activator encoded by a previously uncharacterized gene, copR (previously ybbI). In the copA deficient background the copA-lacZ fusion was super induced to very high levels even in the absence of copper addition to the medium, and this induction was dependent on CopR. These results indicated that the cytoplasmic copper concentration was dramatically increased in the copA mutant, in agreement with the 64Cu uptake experiments. Moreover, they implied, that the copper concentration in wild type cells is determined primarily by the CopA efflux pump, while copper is taken up by an essentially constitutive mechanism.
authors.affiliation: Institute of Molecular Biology, University of Copenhagen, Department of Biological Chemistry, Sølvgade 83H, DK1307 K, Copenhagen, Denmark. carstenpt@mermaid.molbio.ku.dk
authors.forename: C
authors.initials: C
authors.lastname: Petersen
authors.forename: L B
authors.initials: LB
authors.lastname: Møller
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003300:Copper / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology; D003301:Copper Radioisotopes; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006706:Homeostasis; D007763:Lac Operon / Q000235:genetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C071263:CopA protein, Bacteria; D003301:Copper Radioisotopes; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C051124:MerR protein, Bacteria; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; C489822:cueR protein, E coli; D003300:Copper; D000251:Adenosine Triphosphatases