The tcrB gene is part of the tcrYAZB operon conferring copper resistance in Enterococcus faecium and Enterococcus faecalis.
Microbiology (Reading), 2005/9;151(Pt 9):3019-3025.
Hasman H[1]
Affiliations
PMID: 16151212DOI: 10.1099/mic.0.28109-0
Impact factor: 2.956
Abstract
The plasmid-localized tcrB (transferable copper-resistance gene B) gene from Enterococcus faecium was identified to be part of an operon called the tcrYAZB operon, which has a genetic organization similar to the copYZAB copper-homeostasis gene cluster from Enterococcus hirae. Putative promoter (P(tcr))- and repressor-binding sites highly similar to the E. hirae cop-promoter region were identified upstream of the tcrYAZB genes. The P(tcr) promoter was cloned in both the absence and the presence of the proximal repressor-encoding tcrY gene into a promoter-probe vector. Induction of the promoter was shown in liquid growth medium containing increasing concentrations of copper sulphate. To determine the growth advantage conferred by the tcrYAZB genes in a copper environment, a tcr-deletion mutant was isolated, and its growth was compared with that of its copper-resistant ancestor (strain A17sv1) in sublethal concentrations of copper sulphate. A competition assay using these two isogenic strains showed that copper sulphate concentrations of 3 mmol l(-1) and above are sufficient to select for copper resistance.
MeSH terms
Bacterial Proteins; Copper; Enterococcus faecalis; Enterococcus faecium; Operon; Promoter Regions, Genetic; Repressor Proteins; Structure-Activity Relationship
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