ZntB Is a Novel Zn(2+) Transporter in Salmonella enterica Serovar Typhimurium

A Zn(2+) transport system encoded by the zntB locus of Salmonella enterica serovar Typhimurium has been identified. The protein encoded by this locus is homologous to the CorA family of Mg(2+) transport proteins and is widely distributed among the eubacteria. Mutations at zntB confer an increased sensitivity to the cytotoxic effects of Zn(2+) and Cd(2+), a phenotype that suggests that the encoded protein mediates the efflux of both cations. A direct analysis of transport activity identified a capacity for Zn(2+) efflux. These data identify ZntB as a zinc efflux pathway in the enteric bacteria and assign a new function to the CorA family of cation transporters.