CopA: An Escherichia coli Cu(I)-translocating P-type ATPase

The copA gene product, a putative copper-translocating P-type ATPase, has b een shown to be involved in copper resistance in Escherichia coli. The copA gene was disrupted by insertion of a kanamycin gene through homologous rec ombination. The mutant strain was more sensitive to copper salts but not to salts of other metals, suggesting a role in copper homeostasis. The copper -sensitive phenotype could he rescued by complementation by a plasmid carry ing copA from E. coli or copB from Enterococcus hirae. Expression of copA w as induced by salts of copper or silver but not zinc or cobalt. Everted mem brane vesicles from cells expressing copA exhibited ATP-coupled accumulatio n of copper, presumably as Cu(I). The results indicate that CopA is a Cu(I) -translocating efflux pump that is similar to the copper pumps related to M enkes and Wilson diseases and provides a useful prokaryotic model for these human diseases.