Induction of the putative copper ATPases, CopA and CopB, of Enterococcus hirae by Ag+ and Cu2+, and Ag+ extrusion by CopB.

The two P-type ATPases CopA and CopB are effecting regulation of cellular copper activity in Enterococcus hirae. With antibodies against these ATPases, we showed on Western blots the simultaneous induction of CopA and CopB by copper or silver ions. Copper contents of wild type and mutant cells lacking either CopA, CopB or both enzymes were measured by atomic absorption. Strains disrupted in copB showed clearly enhanced copper contents. Mutants lacking CopB also lost the ability of energy dependent efflux of silver ions. Our results demonstrate that CopA and CopB are under the same genetic control and support the proposal that CopB is a copper and silver exporting ATPase.