Anton A, Grosse C, Reissmann J, Pribyl T, Nies D H
Institut für Mikrobiologie, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany.
J Bacteriol. 1999 Nov;181(22):6876-81. doi: 10.1128/JB.181.22.6876-6881.1999.
The Czc system of Ralstonia sp. strain CH34 mediates resistance to cobalt, zinc, and cadmium through ion efflux catalyzed by the CzcCB(2)A cation-proton antiporter. The CzcD protein is involved in the regulation of the Czc system. It is a membrane-bound protein with at least four transmembrane alpha-helices and is a member of a subfamily of the cation diffusion facilitator (CDF) protein family, which occurs in all three domains of life. The deletion of czcD in a Ralstonia sp. led to partially constitutive expression of the Czc system due to an increased transcription of the structural czcCBA genes, both in the absence and presence of inducers. The czcD deletion could be fully complemented in trans by CzcD and two other CDF proteins from Saccharomyces cerevisiae, ZRC1p and COT1p. All three proteins mediated a small but significant resistance to cobalt, zinc, and cadmium in Ralstonia, and this resistance was based on a reduced accumulation of the cations. Thus, CzcD appeared to repress the Czc system by an export of the inducing cations.
罗尔斯通氏菌属CH34菌株的Czc系统通过CzcCB(2)A阳离子-质子反向转运体催化的离子外流介导对钴、锌和镉的抗性。CzcD蛋白参与Czc系统的调控。它是一种膜结合蛋白，至少有四个跨膜α螺旋，是阳离子扩散促进剂（CDF）蛋白家族一个亚家族的成员，该家族存在于生命的所有三个域中。罗尔斯通氏菌属中czcD的缺失导致Czc系统部分组成型表达，这是由于在有无诱导剂的情况下，结构基因czcCBA的转录增加。czcD的缺失可以通过来自酿酒酵母的CzcD和其他两种CDF蛋白ZRC1p和COT1p进行反式完全互补。这三种蛋白在罗尔斯通氏菌属中均介导了对钴、锌和镉的微弱但显著的抗性，且这种抗性基于阳离子积累的减少。因此，CzcD似乎通过诱导阳离子的输出抑制Czc系统。
