Two MerR homologues that affect copper induction of the Bacillus subtilis copZA operon
Two MerR homologues that affect copper induction of the Bacillus subtilis copZA operon
复制标题
DOI：
10.1099/mic.0.26225-0
复制
发表时间：
2003-12-01
期刊：
影响因子：
2.8
通讯作者：
Helmann, JD
中科院分区：
文献类型：
--
作者：
Gaballa, A;Cao, M;Helmann, JD
铜离子诱导枯草芽孢杆菌 copZA 操纵子的表达，该操纵子编码金属伴侣蛋白 CopZ 和 CPx 型 ATP 酶流出蛋白 Cook。 copZA 启动子区域包含与汞感应 MerR 蛋白识别的相似的反向重复序列。为了研究 MerR 同源物在 copZA 调控中的可能参与，设计了无效突变，影响四种假定的 MerR 型调控因子：yyaN、yraB、yfmP 和 yhdQ。其中两个基因影响铜调节。 yhdQ（以下更名为cueR）的突变显着降低了copZA的铜诱导，并且纯化的CueR以高亲和力与copZA启动子区域结合。这些结果表明 CueR 是介导铜诱导的 copZA 转录的直接调节因子。令人惊讶的是，yfmP 突变也降低了 copZA 的铜诱导。序列分析表明 yfmP 与 yfmO 共转录，编码假定的多药外排蛋白。 yfmPO 操纵子是自动调节的：yfmP 突变解除了 yfmP 启动子的抑制，纯化的 YfmP 结合 yfmP 启动子区域，但不结合 copZA 启动子区域。由于预计 yfmP 突变株会表达升高水平的 YfmO 外排泵，因此推测铜外排可能是 copZA 诱导减少的原因。与该模型一致，在 yfmP yfmO 双突变体中，copZA 的铜诱导是正常的。结果证明了 CueR 对枯草芽孢杆菌铜流出系统的直接调节，以及假定的多药物流出系统的间接调节。
Copper ions induce expression of the Bacillus subtilis copZA operon encoding a metallochaperone, CopZ, and a CPx-type ATPase efflux protein, Cook The copZA promoter region contains an inverted repeat sequence similar to that recognized by the mercury-sensing MerR protein. To investigate the possible involvement of MerR homologues in copZA regulation, null mutations were engineered affecting each of four putative MerR-type regulators: yyaN, yraB, yfmP and yhdQ. Two of these genes affected copper regulation. Mutation of yhdQ (hereafter renamed cueR) dramatically reduced copper induction of copZA, and purified CueR bound with high affinity to the copZA promoter region. These results suggest that CueR is a direct regulator of copZA transcription that mediates copper induction. Surprisingly, a yfmP mutation also reduced copper induction of copZA. Sequence analysis suggested that yfmP was cotranscribed with yfmO, encoding a putative multidrug efflux protein. The yfmPO operon is autoregulated: a yfmP mutation derepressed the yfmP promoter and purified YfmP bound the yfmP promoter region, but not the copZA promoter region. Since the yfmP mutant strain was predicted to express elevated levels of the YfmO efflux pump, it was hypothesized that copper efflux might be responsible for the reduced copZA induction. Consistent with this model, in a yfmP yfmO double mutant copper induction of copZA was normal. The results demonstrate the direct regulation of the B. subtilis copper efflux system by CueR, and indirect regulation by a putative multidrug efflux system.