Interplay of the Czc system and two P-type ATPases in conferring metal resistance to XXXX .

@entity526 @entity219 @entity72860 @entity3409
@entity3409 and @entity219 are removed from cells of @entity72860 by the CzcCBA efflux pump and by two soft-metal-transporting P-type ATPases, CadA and ZntA. The czcCBA genes are located on plasmid pMOL30, and the cadA and zntA genes are on the bacterial chromosome. Expression of zntA from @entity72860 in @entity526 predominantly mediated resistance to @entity219 , and expression of cadA predominantly mediated resistance to @entity3409 . Both transporters decreased the cellular content of @entity219 or @entity3409 in this host. In the plasmid-free @entity72860 AE104, single gene deletions of cadA or zntA had only a moderate effect on @entity3409 and @entity219 resistance, but @entity219 resistance decreased 6-fold and @entity3409 resistance decreased 350-fold in double deletion strains. Neither single nor double gene deletions affected @entity219 resistance in the presence of czcCBA. In contrast, @entity3409 resistance of the cadA zntA double mutant could be elevated only partially by the presence of CzcCBA. lacZ reporter gene fusions indicated that expression of cadA was induced by @entity3409 but not by @entity219 in @entity72860 AE104. In the absence of the zntA gene, expression of cadA occurred at lower @entity3409 concentrations and @entity219 now served as an inducer. In contrast, expression of zntA was induced by both @entity219 and @entity3409 , and the induction pattern did not change in the presence or absence of CadA. However, expression of both genes, zntA and cadA, was diminished in the presence of CzcCBA. This indicated that CzcCBA efficiently decreased cytoplasmic @entity3409 and @entity219 concentrations. It is discussed whether these data favor a model in which the cations are removed either from the cytoplasm or the periplasm by CzcCBA.
