Grosse Cornelia, Anton Andreas, Hoffmann Toni, Franke Sylvia, Schleuder Grit, Nies Dietrich H
Institut für Mikrobiologie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 3, 06099 Halle, Germany.
Arch Microbiol. 2004 Oct;182(2-3):109-18. doi: 10.1007/s00203-004-0670-8. Epub 2004 Aug 31.
The CzcCBA cation-proton-antiporter is the most complicated and efficient heavy-metal resistance system known today and is essential for survival of Ralstonia metallidurans at high cobalt, zinc, or cadmium concentrations. Expression of Czc is tightly controlled by the complex interaction of several regulators. Double- and multiple-deletion studies demonstrated that four regulators encoded downstream of the czcCBA operon, CzcD, CzcS, CzcR and the newly identified CzcE, are involved in, but not essential for metal-dependent induction of czc. These proteins control expression of the czcNICBA region from the promoter czcNp. Northern analysis showed that czcDRS was transcribed as czcDR-specific and czcDRS-specific mRNAs. Transcription of czcE occurred independently of czcDRS transcription and was induced by zinc. CzcE is a periplasmic protein as indicated by phoA fusions. CzcE was purified and identified as a metal-binding protein. These data demonstrate that the transport protein CzcD, the two-component regulatory system CzcR, CzcS, and the periplasmic metal-binding protein CzcE exert metal-dependent control of czcNICBA expression via regulation of czcNp activity.
CzcCBA阳离子-质子反向转运蛋白是目前已知最为复杂且高效的重金属抗性系统，对于嗜金属贪铜菌在高钴、锌或镉浓度环境下的生存至关重要。Czc的表达受到多种调控因子复杂相互作用的严格控制。双缺失和多缺失研究表明，位于czcCBA操纵子下游编码的四个调控因子，即CzcD、CzcS、CzcR以及新鉴定出的CzcE，参与但并非金属依赖性诱导czc所必需。这些蛋白质从启动子czcNp控制czcNICBA区域的表达。Northern分析表明，czcDRS转录为czcDR特异性和czcDRS特异性mRNA。czcE的转录独立于czcDRS转录，并受锌诱导。如phoA融合所示，CzcE是一种周质蛋白。CzcE经纯化后被鉴定为一种金属结合蛋白。这些数据表明，转运蛋白CzcD、双组分调控系统CzcR、CzcS以及周质金属结合蛋白CzcE通过调节czcNp活性对czcNICBA表达发挥金属依赖性控制作用。
