琥珀酸盐调节肠出血性大肠杆菌O157:H7毒性的分子机制

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 are important human gastrointestinal pathogens which causes severe diseases. During infection, EHEC O157:H7 sensing a series of intestinal signals to recognize human large intestines as its optimal colonization site through regulating the expression of virulence genes. Our preliminary work revealed that succinate significantly enhance the ability of EHEC O157:H7 to adhere to host epithelial cell and to express virulence genes, indicating succinate is involved in the EHEC O157:H7 virulence regulation. However, the mechanisms behind are still not well known. This project will focus on the molecular mechanisms of succinate mediated EHEC O157:H7 virulence regulation. We will combine transcriptome and random mutant library-high throughput screening technologies to screen systematically and integrally all bacterial sensing proteins and regulatory proteins which involved in succinate.mediated EHEC O157:H7 virulence regulation. On this basis, we will determine the order and the regulatory ways (direct regulation or indirect regulation), as well as the precise binding sites of these proteins, ultimately, to explore succinate mediated EHEC O157:H7 virulence regulatory pathways. The outcome of this project will largely enrich our understanding on EHEC O157:H7 virulence regulatory network and pathogenicity mechanisms. The key genes in succinate mediated EHEC O157:H7 virulence regulatory pathways provide potential targets for vaccines and antibacterial drugs development, as well as novel ideas to prevent EHEC O157:H7 infection.

肠出血性大肠杆菌（EHEC）O157:H7是重要的人类肠道致病菌。在致病过程中，该致病菌需要感受一系列肠道信号，通过精确调控相关毒力基因的表达来识别其定植位点（大肠）。我们前期工作发现，琥珀酸盐能够显著增强EHEC O157:H7吸附宿主上皮细胞和表达毒力基因的能力，但精确机制还不清楚。本项目拟结合转录组测序、随机突变体库高通量筛选、分子生物学等技术，全面、系统筛选琥珀酸盐毒性调节通路中的全部细菌表面传感蛋白和调节蛋白，确定各蛋白的作用顺序、调节方式（直接调控或间接调控）和调节位点，最终精确解析琥珀酸盐介导的EHEC O157:H7毒性调节机制。本项目的研究结果对于全面深入理解EHEC O157:H7的致病机制和进化机制具有重要意义。同时，本项目鉴定出的琥珀酸盐介导的毒性调节通路中的关键基因可以做为疫苗和相关药物的候选靶点，为EHEC O157:H7引起感染的预防和治疗提供新的方法与思路。