鞭毛是细菌的重要运动器官。对于许多病原菌的感染能力具有显著影响。编码相关组分蛋白质的基因受到严格的调控。FlhD4C2复合物处于整个流程的最前端，作为转录因子启动下游基因的表达。YdiV能够与FlhD4C2形成超级复合物关闭相关基因的表达。我们最近的研究工作表明，YdiV对FlhD4C2的抑制作用存在一个浓度阈值。低于这个阈值则没有抑制作用。另一个蛋白质FliT作为分子伴侣协助鞭毛蛋白质的转运，同时还可以与FlhD4C2复合物相互作用抑制下游基因的表达。本项目计划通过测定YdiV-FlhD4C2、FliT-FlhD4C2超级复合物以及相关蛋白质复合物的结构，系统地阐明这两种蛋白质抑制鞭毛基因表达的分子机制。并比较两种蛋白质抑制机制的不同之处及其对细菌生存的生理意义。

Bacterial flagellum is important locomotive organelle。It determinates the ability of infection for many pathogenic bacteria. Expressions of flagellar genes are tightly regulated.At the top of the hierarchy is the flhDC operon, whose expression is required for the transcription of all other flagellar operons.YdiV represses bacterium motility by interacting with FlhD4C2 complex.Our recent work shows the inhibition of YidV on FlhD4C2 is concentratin dependent and a threshold of concentration exists.Once the YdiV concentration lower than the threshold, the inhibition does not exist. Another protein FliT, works as a chaperone to facilitate transort of flagellum proteins can also inhibit FlhD4C2 throgh direct interaction.We plan to determinate the three dimentional structures of YdiV-FlhD4C2, FliT-FlhD4C2 and other protein complex structures involved in this process. Base on the structures the molecular mechanism by which YdiV and FliT inhibit flagellum biogenesis could be elucidated.We also plan to clarify why YdiV and FliT play role in different patern and the physiological significance for bacteria.