Munkelt Doreen, Grass Gregor, Nies Dietrich H
Institut für Mikrobiologie, Martin-Luther-Universität Halle, Kurt-Mothes-Str. 3, 06120 Halle, Germany.
J Bacteriol. 2004 Dec;186(23):8036-43. doi: 10.1128/JB.186.23.8036-8043.2004.
Genomic sequencing of the beta-proteobacterium Wautersia (previously Ralstonia) metallidurans CH34 revealed the presence of three genes encoding proteins of the cation diffusion facilitator (CDF) family. One, CzcD, was previously found to be part of the high-level metal resistance system Czc that mediates the efflux of Co(II), Zn(II), and Cd(II) ions catalyzed by the CzcCBA cation-proton antiporter. The second CDF protein, FieF, is probably mainly a ferrous iron detoxifying protein but also mediated some resistance against other divalent metal cations such as Zn(II), Co(II), Cd(II), and Ni(II) in W. metallidurans or Escherichia coli. The third CDF protein, DmeF, showed the same substrate spectrum as FieF, but with different preferences. DmeF plays the central role in cobalt homeostasis in W. metallidurans, and a disruption of dmeF rendered the high-level metal cation resistance systems Czc and Cnr ineffective against Co(II). This is evidence for the periplasmic detoxification of substrates by RND transporters of the heavy metal efflux family subgroup.
对β-变形菌嗜金属沃氏菌（以前称为嗜金属罗尔斯通氏菌）CH34进行的基因组测序显示，存在三个编码阳离子扩散促进因子（CDF）家族蛋白质的基因。其中一个基因CzcD，先前被发现是高水平金属抗性系统Czc的一部分，该系统介导由CzcCBA阳离子-质子反向转运蛋白催化的Co（II）、Zn（II）和Cd（II）离子的外排。第二个CDF蛋白FieF可能主要是一种亚铁解毒蛋白，但也介导了嗜金属沃氏菌或大肠杆菌对其他二价金属阳离子如Zn（II）、Co（II）、Cd（II）和Ni（II）的一定抗性。第三个CDF蛋白DmeF显示出与FieF相同的底物谱，但偏好不同。DmeF在嗜金属沃氏菌的钴稳态中起核心作用，dmeF的破坏使高水平金属阳离子抗性系统Czc和Cnr对Co（II）无效。这证明了重金属外排家族亚组的RND转运蛋白对底物进行周质解毒。
