Rensing C, Sun Y, Mitra B, Rosen B P
Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, Detroit, Michigan 48201, USA.
J Biol Chem. 1998 Dec 4;273(49):32614-7. doi: 10.1074/jbc.273.49.32614.
The cad operon of Staphylococcus aureus plasmid pI258, which confers cadmium resistance, encodes a transcriptional regulator, CadC, and CadA, an ATP-coupled Cd(II) pump that is a member of the superfamily of cation-translocating 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 hypothesis that ZntA and CadA are Pb(II) pumps. First, CadC is a metal-responsive repressor that responds to soft metals in the order Pb>Cd>Zn. Second, both CadA and ZntA confer resistance to Pb(II). Third, transport of 65Zn(II) in everted membrane vesicles of E. coli catalyzed by either of these two P-type ATPase superfamily members is inhibited by Pb(II).
金黄色葡萄球菌质粒pI258的镉操纵子赋予细菌对镉的抗性，它编码一个转录调节因子CadC和CadA，CadA是一种与ATP偶联的Cd（II）泵，属于阳离子转运P型ATP酶超家族的成员。CadA在大肠杆菌中的同源物称为ZntA，是一种Zn（II）/Cd（II）泵。本文所述结果支持ZntA和CadA是Pb（II）泵的假说。首先，CadC是一种金属反应性阻遏物，对软金属的反应顺序为Pb>Cd>Zn。其次，CadA和ZntA都赋予对Pb（II）的抗性。第三，这两种P型ATP酶超家族成员中的任何一种催化的大肠杆菌外翻膜囊泡中65Zn（II）的转运都受到Pb（II）的抑制。
