A three-component signalling system fine-tunes expression kinetics of HPPK responsible for folate synthesis by positive feedback loop during stress response of Xanthomonas campestris.
A three-component signalling system fine-tunes expression kinetics of HPPK responsible for folate synthesis by positive feedback loop during stress response of Xanthomonas campestris.
复制标题
DOI：
10.1111/1462-2920.12293
复制
发表时间：
2014-07
影响因子：
5.1
通讯作者：
Fang-Fang Wang-Fang;Chao-Ying Deng;Zhen Cai;Ting Wang;Li Wang;Xiao-Zheng Wang;Xiao-ying Chen;R. Fang;W. Qian
中科院分区：
文献类型：
--
作者：
Fang-Fang Wang-Fang;Chao-Ying Deng;Zhen Cai;Ting Wang;Li Wang;Xiao-Zheng Wang;Xiao-ying Chen;R. Fang;W. Qian
在适应环境的过程中，细菌采用双组分信号转导系统，其中包含组氨酸激酶和反应调节因子，以准确的时空方式感知和响应外源和细胞刺激。虽然组氨酸激酶与应答调节因子之间的蛋白磷酸化过程已被充分记载，但调控应答调节因子磷酸化水平的分子机制研究相对较少。本研究结合遗传和生化方法，揭示了一种杂化组氨酸激酶SreS参与了油菜黄单胞菌SreK-SreR磷传递过程，从而控制了盐胁迫反应。SreS的n端受体结构域通过与反应调节因子SreR竞争来接受来自后者同源组氨酸激酶SreK的磷酸化基团，从而充当磷酸盐汇。这一调控过程对细菌存活至关重要，因为去磷酸化的SreR蛋白参与激活sreK-sreR-sreS-hppK操纵子5'端的串联启动子之一（P2），然后调节应激反应基因hppK的转录高潮，这是叶酸合成所必需的。因此，我们的研究剖析了一个正反馈回路的生化过程，其中“三组分”信号系统微调下游基因的表达动力学。
During adaptation to environments, bacteria employ two-component signal transduction systems, which contain histidine kinases and response regulators, to sense and respond to exogenous and cellular stimuli in an accurate spatio-temporal manner. Although the protein phosphorylation process between histidine kinase and response regulator has been well documented, the molecular mechanism fine-tuning phosphorylation levels of response regulators is comparatively less studied. Here we combined genetic and biochemical approaches to reveal that a hybrid histidine kinase, SreS, is involved in the SreK-SreR phosphotransfer process to control salt stress response in the bacterium Xanthomonas campestris. The N-terminal receiver domain of SreS acts as a phosphate sink by competing with the response regulator SreR to accept the phosphoryl group from the latter's cognate histidine kinase SreK. This regulatory process is critical for bacterial survival because the dephosphorylated SreR protein participates in activating one of the tandem promoters (P2) at the 5' end of the sreK-sreR-sreS-hppK operon, and then modulates a transcriptional surge of the stress-responsive gene hppK, which is required for folic acid synthesis. Therefore, our study dissects the biochemical process of a positive feedback loop in which a 'three-component' signalling system fine-tunes expression kinetics of downstream genes.