Effects of promoter mutations on the in vivo regulation of the cop operon of Enterococcus hirae by copper(I) and copper(II).

Department of Clinical Pharmacology, University of Berne, Berne, 3010, Switzerland.
Biochemical and Biophysical Research Communications (Impact Factor: 2.28). 07/1999; 259(2):443-9. DOI: 10.1006/bbrc.1999.0807
Source: PubMed

ABSTRACT The cop operon of Enterococcus hirae encodes a repressor, CopY, a copper chaperone, CopZ, and two copper ATPases, CopA and CopB. Regulation of the cop operon is bi-phasic, with copper addition as well as copper chelation leading to induction. Using a plasmid-borne system with a reporter gene, induction of wild-type and mutant cop promoters by high and low copper conditions was investigated. Only mutations that impaired the interaction of CopY with both DNA binding sites had a marked effect on regulation, leading to hyperinduction by copper(I) or copper(II). Chelation of copper(II), but not copper(I), also induced the operon, but induction by copper chelation was not significantly affected by the mutations. E. hirae mutants with reduced extracellular copper reductase activity exhibited the same induction kinetics as wild-type cells. These results show that copper addition and copper chelation induce the cop operon by different routes.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cu being a transition metal is ubiquitously engaged in biological systems to derive electrons through its participation in several enzymatic reactions. Upon bestowing the significance of Cu in biological systems, an elaborate mechanism is set forth by nature for maintaining Cu homeostasis. As a consequence, a wide variety of proteins viz., family of Cu bearing proteins, cuproenzymes, Cu transporters and Cu chaperone proteins have been manifested for enabling Cu to show its relevance in biological health. In addition, understanding the role of Cu in hepatic and neuronal functions and also in angiogenesis keeps progressing with the advent of novel molecular tools. The studies on genetic defects in Cu metabolism causing abnormalities are providing insights leading to the possible prognostic cues to alleviate the sufferings.
    The Indian Journal of Medical Research 11/2008; 128(4):448-61. · 2.06 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Helicobacter pylori (H. pylori) have a unique ability to survive in extreme acidic environments and to colonize the gastric mucosa. It can cause diverse gastric diseases such as peptic ulcers, chronic gastritis, mucosa-associated lymphoid tissue (MALT) lymphoma, gastric cancer, etc. Based on genomic research of H. pylori, over 1600 genes have been functionally identified so far. However, H. pylori possess some genes that are uncharacterized since: (i) the gene sequences are quite new; (ii) the function of genes have not been characterized in any other bacterial systems; and (iii) sometimes, the protein that is classified into a known protein based on the sequence homology shows some functional ambiguity, which raises questions about the function of the protein produced in H. pylori. Thus, there are still a lot of genes to be biologically or biochemically characterized to understand the whole picture of gene functions in the bacteria. In this regard, knowledge on the 3D structure of a protein, especially unknown or hypothetical protein, is frequently useful to elucidate the structure-function relationship of the uncharacterized gene product. That is, a structural comparison with known proteins provides valuable information to help predict the cellular functions of hypothetical proteins. Here, we show the 3D structures of some hypothetical proteins determined by NMR spectroscopy and X-ray crystallography as a part of the structural genomics of H. pylori. In addition, we show some successful approaches of elucidating the function of unknown proteins based on their structural information.
    International Journal of Molecular Sciences 01/2012; 13(6):7109-37. · 2.46 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Environmental copper contamination is a serious human health problem. Copper reductase is produced by microorganisms to facilitate copper uptake by ATPases into the cells increasing copper biosorption. This study assessed the reduction of Cu(II) by cell-free extracts of a highly copper-resistant bacterium, Pseudomonas sp. strain NA, isolated from vineyard soil contaminated with copper. Both intact cells and cell-free extract of Pseudomonas sp. strain NA displayed substantial reduction of Cu(II). Intact cells reduced more then 80 mg L(-1) of Cu(II) from medium amended with 200 mg L(-1) of copper after 24 h of incubation. Cell-free extract of the isolate reduced more than 65% of the Cu(II) at initial copper concentration of 200 mg L(-1) after 24 h. Soluble protein production was high at 72 h of incubation at 100 mg L(-1) of copper, with more then 60 μg L(-1) of total soluble protein in cell-free extract recorded. Cu(II) reduction by isolate NA was increased when copper concentration increased for both intact cells and cell-free extract. Results indicate that Pseudomonas sp. strain NA produces copper reductase enzyme as the key mechanism of copper biotransformation.
    Biological trace element research 11/2010; 143(2):1182-92. · 1.92 Impact Factor

Full-text (2 Sources)

Available from
Sep 14, 2014