Pb(II)-translocating P-type ATPases

The cad operon of Staphylococcus aureus plasmid pI258, which confers cadmiu m resistance, encodes a transcriptional regulator, CadC, and CadA, an ATP-c oupled Cd(II) pump that is a member of the superfamily of cation-translocat ing P-type ATPases, The Escherichia coli homologue of CadA, termed ZntA, is a Zn(II)/Cd(II) pump. The results described in this paper support the hypo thesis that ZntA and CadA are Pb(II) pumps, First, CadC is a metal-responsi ve repressor that responds to soft metals in the order Pb>Cd>Zn, Second, bo th CadA and ZntA confer resistance to Pb(II), Third, transport of Zn-65(II) in everted membrane vesicles of E. coli catalyzed by either of these two P -type ATPase superfamily members is inhibited by Pb(II).