双组分信号转导系统（Two-component System, TCS）调控着细菌的大部分生命活动，是最具潜力的新型抗菌药物靶标之一。细菌的TCS由组氨酸激酶HK和反应调节蛋白RR两部分组成，以磷酸传递的方式实现信号转导从而启动细胞应答。至今尚不明确反应调节蛋白RR如何接受来自组氨酸激酶HK的磷酸基团从而实现活化。我们发现HK上较为动态的ATP lid影响磷酸传递过程却不影响HK的其它功能。本项目拟选用模式蛋白HK853-RR468为研究对象，运用核磁共振动态研究、蛋白质交联、基因突变、同位素标记、酶活测试等技术，在复合物层次上捕捉低丰度瞬态构象并阐述蛋白质结构、动态和功能之间的联系，从原子水平上揭示HK853的ATP lid在磷酸传递过程中对RR活化的作用。该研究将有助于深入理解细菌的信号转导机理，为新型抗菌药物的设计提供理论依据，用以抗击日益严重的“超级细菌”。

Two-component systems (TCS) regulate most important life processes of bacteria, which are potential targets of novel antibacterial drugs. A typical TCS consists of a histidine kinase (HK) and a response regulator (RR), transducing signals through phosphotransfer to trigger cellular regulation. It is not clear how response regulators are activated by receiving phosphoryl group from histidine kinases. Interestingly, we found that the dynamic ATP lid of HK plays an important role in phosphotransfer between HK and RR, but does not affect other functions of HK. In this project, HK853-RR468 was chosen as a model TCS. Low-population transient conformations would be investigated in the form of protein complex by using NMR technology, isotope labeling and protein cross-linking technology. Furthermore, the mechanism of RR activation regulated by ATP lid of HK853 through phosphotransfer would be elucidated in combination with gene mutagenesis and enzymologic assays. In light of the relationships between structure, dynamics and functions, the study would give us a better understanding on the mechanisms of two-component signal transduction systems and provide us theory basis for designing antibacterial drugs to beat back “super bacteria”.