THE ZNTA GENE OF ESCHERICHIA-COLI ENCODES A ZN(II)-TRANSLOCATING P-TYPE ATPASE

The first Zn(II)-translocating P-type ATPase has been identified as th e product of o732, a potential gene identified in the sequencing of th e Escherichia coli genome, This gene, termed zntA, was disrupted by in sertion of a kanamycin gene through homologous recombination. The muta nt strain exhibited hypersensitivity to zinc and cadmium salts but not salts of other metals, suggesting a role in zinc homeostasis in E. co li. Everted membrane vesicles from a wild-type strain accumulated Zn-6 5(II) and Cd-109(II) by using ATP as an energy source, Transport was s ensitive to vanadate, an inhibitor of P-type ATPases. Membrane vesicle s from the zntA::kan strain did not accumulate those metal ions, Both the sensitive phenotype and transport defect of the mutant were comple mented by expression of zntA on a plasmid.