FB Biologie/Chemie, Angewandte Genetik der Mikroorganismen, Universität Osnabrück, Barbarastr. 13, 49069, Osnabrück, Germany.
Amino Acids. 2009 Oct;37(4):681-91. doi: 10.1007/s00726-008-0188-5. Epub 2008 Oct 19.
The SenS/SenR system of Streptomyces reticuli regulates the expression of the redox regulator FurS, the catalase-peroxidase CpeB and the heme-binding protein HbpS. SenS/SenR is also proposed to participate in sensing redox changes, mediated by HbpS. Here, we show in vitro that heme-free HbpS represses the autokinase activity of SenS; whereas hemin-treated HbpS considerably enhances SenS autophosphorylation under redox conditions using either H(2)O(2) or DTT. The presence of iron ions alone or in combination with H(2)O(2) or DTT also leads to significantly increased phosphorylation levels of SenS. Further comparative physiological studies using the S. reticuli WT, a S. reticuli hbpS mutant and a S. reticuli senS-senR mutant corroborates the importance of HbpS and the SenS/SenR system for resistance against high concentrations of iron ions and hemin in vivo. Hence SenS/SenR and HbpS act in concert as a novel three-component system which detects redox stress, mediated by iron ions and heme.
链霉菌属的 SenS/SenR 系统调节氧化还原调节剂 FurS、过氧化氢酶过氧化物酶 CpeB 和血红素结合蛋白 HbpS 的表达。SenS/SenR 还被提议参与由 HbpS 介导的氧化还原变化的感应。在这里，我们在体外表明无血红素的 HbpS 抑制 SenS 的自激酶活性；而在用 H2O2 或 DTT 处理的血红素处理的 HbpS 下，在氧化还原条件下，显著增强了 SenS 的自动磷酸化。单独存在铁离子或与 H2O2 或 DTT 结合存在也会导致 SenS 的磷酸化水平显著增加。使用链霉菌属 WT、链霉菌属 hbpS 突变体和链霉菌属 senS-senR 突变体进行的进一步比较生理研究证实了 HbpS 和 SenS/SenR 系统在体内对高浓度铁离子和血红素的抗性的重要性。因此，SenS/SenR 和 HbpS 作为一种新型的三组分系统协同作用，该系统通过铁离子和血红素来检测氧化还原应激。
