铜绿假单胞菌中参与急-慢性感染转化的Ⅲ分泌系统调控途径及机理研究

Pseudomonas aeruginosa is an important pathogen, causing serious and often life-threatening infections in humans. It can cause both invasive, acute infections and also chronic infections that are extremely difficult to treat. Type III secretion system (T3SS) is an essential virulence factor for P. aeruginosa acute infections. The regulation of T3SS is not only important for P. aeruginosa pathogenicity but also for its transition from acute infection to chronic infection. The down-regulation of T3SS and up-regulation of biofilm formation are the hallmarks of P. aeruginosa establishing chronic infections. The major aim of this proposal is to investigate the regulatory networks that control T3SS and are involved in the infection transition process. The new infection transition regulators PA1611, previously identified in our laboratory, will be characterized both biochemically and genetically. The detail structural basis for PA1611-RetS interaction will be analyzed by using BacterioMatch II Two-Hybrid System and point-directed mutagenesis.

铜绿假单胞菌（Pseudomonas aeruginosa）是人类病原菌，可引起危害严重的急性感染和难以治愈的慢性感染。Ⅲ型分泌系统是其最重要的致病因子之一，不仅参与致病过程，它的表达变化也与急性感染向慢性感染的转化密切相关。本项目旨在研究铜绿假单胞菌Ⅲ分泌系统的调控途径及机理，尤其是与急-慢性感染转化相关的调控系统。针对前期鉴定的感染转化调节子PA1611，研究其功能及其介导的信号传递途径。利用双杂交系统和定点突变等方法研究PA1611的结构与功能关系。

本项目的研究焦点是人类病原菌铜绿假单胞菌中是与急-慢性感染转化相关的Ⅲ分泌系统的调控途径及机理。铜绿假单胞菌可引起危害严重的急性感染和难以治愈的慢性感染。Ⅲ型分泌系统是其最重要的致病因子之一，不仅参与致病过程，它的表达变化也与急性感染向慢性感染的转化密切相关。项目针对前期鉴定的感染转化调节子PA1611，对其功能及其介导的信号传递途径进行了研究。使用细菌双杂交实验，完成检验PA1611与RetS, GacS及LadS的相互作用。确定了PA1611与Gac-RsmA调控系统的关系，揭示了PA1611通过与RetS直接作用影响GacS磷酸化，进而调节小RNA rsmY/Z的作用机理。分析完成了PA1611与RetS的作用位点，并完成PA1611，RetS 和GacS体外蛋白相互作用试验。本项目是为期一年的小额探索性面上项目，课题组按照计划，完成了研究计划中所有的研究内容。并在此基础上，在个别方面有所扩展，针对PA1611的结构以及相关的调控因子PA4595的进一步研究仍在进行中。