TCS01双组分系统对胆碱结合蛋白PcpA的转录调控机制及其在肺炎链球菌致病过程中的作用

肺炎链球菌依赖双组分系统（TCSs）调控致病性、渗透压、趋化性及能量代谢等过程。目前TCS01(HK/RR01)调控肺炎链球菌致病性的机制并不清楚。前期研究我们发现TCS01突变株致病性降低，且TCS01能够直接转录调控胆碱结合蛋白PcpA。PcpA介导细菌对宿主的黏附力，参与细菌致病性，是潜在疫苗靶标。因此推测TCS01可能通过调控PcpA从而影响肺炎链球菌致病性。本研究拟利用EMSA及DNaseI足迹分析实验鉴定TCS01所结合的PcpA启动子位点；应用结构生物学方法，发现RR01在转录调控PcpA过程中的构像变化及特异性结合位点；验证TCS01转录调控PcpA对菌株致病性的关键作用；阐明TCS01通过转录调控PcpA从而影响肺炎链球菌致病性的分子机制。最终阐释TCS01转录调控PcpA的机制及其在细菌致病过程中的作用。这将为开发新型抗肺炎链球菌感染的药物靶标提供实验基础及理论指导。

Streptococcus pneumonia (S. pneumonia) relies on two-component systems (TCSs) to regulate the process of pathogenicity, osmotic pressure, chemotaxis and energy metabolism. At present the mechanism of TCS01 (HK/RR01) regulating the pathogenicity of S. pneumonia is unclear. Our previous study has showed that TCS01 mutant strain exhibits attenuated pathogenicity, and TCS01 system directly transcriptionally regulates choline binding protein PcpA. PcpA mediates bacterial adhesion to the host, participates in the pathogenicity. And PcpA is a potential vaccine target. In this study, the PcpA promoter sites bound by TCS01 will be identified by EMSA and DNase I footprinting. The conformational change and specific binding sites of RR01 in transcriptional regulation of PcpA will be found by structural biology method. The key role of TCS01 transcriptional regulation of PcpA on pathogenicity of S. pneumonia will be verified. The molecular mechanism of TCS01 system influence the pathogenicity of S. pneumonia through transcriptionally regulating PcpA will be expounded. Finally, the transcriptional regulation mechanism of TCS01 on PcpA and its role on the pathogenic process of S. pneumonia will be elaborated. This study will provide experimental basis and theoretical guidance for the development of novel drug targets against streptococcus pneumoniae infection.