SlmA调节霍乱弧菌肠道定植的分子机制研究

Vibrio cholerae is one of the most notorious human enteric pathogens worldwide, which poses a serious threat to human health. Colonizing the small intestine effectively is a basis process to cause diarrheal disease cholera, and multiple factors are involved in this process. However, functions of these factors have not been comprehensive so far. In the previous work, we found that the mutation of slmA causes decreased intestinal colonization of V. cholerae, which is a new function that has never been reported before. The previous studies of SlmA mainly focused on its impact on binary fission, and the mechanism of its function in intestinal colonization is not yet clear. In this project, the molecular mechanism that SlmA involved in intestinal colonization will be chosen for further study using high-throughput sequencing, molecular biological and biochemical methods. On the one hand, the target genes of SlmA which play roles in intestinal colonization will be identified and determined; on the other hand, which and how environmental signals and senior regulatory factors regulate the expression of slmA will be investigated. The results will reveal the molecular mechanism that SlmA involved in intestinal colonization, which is of great significance for understanding the pathogenesis and regulatory network of V. cholerae. Besides, virulence genes found in this project can be used as candidate targets for vaccines and medicines, which is a new strategy for the treatment of V. cholerae infection.

霍乱弧菌是重要的肠道致病菌，严重威胁着人类健康。肠道定植是其致病的前提，该过程由多种因子共同参与，但目前对这些因子的功能研究并不全面。申请人前期发现，缺失具有转录调控功能的蛋白SlmA后，霍乱弧菌的肠道定植能力显著下降，说明SlmA对霍乱弧菌的肠道定植有重要影响。以前对SlmA的研究主要集中在其对细菌二分裂的作用，而对该蛋白作用于肠道定植这一新功能的机制尚无报道。因此，本项目拟结合高通量组学、分子生物学及生物化学等多种技术手段，对SlmA调节肠道定植过程的分子机制进行深入研究。一方面，系统解析SlmA所调节的肠道定植相关靶基因及其调控方式；另一方面，探究影响slmA基因表达的肠道环境信号及高级调节因子；最终构建SlmA蛋白的整体调控网络。研究成果将丰富人们对SlmA蛋白功能的认识，对于全面剖析霍乱弧菌的肠道定植调控网络和致病机理具有重要意义，并可为霍乱的预防和治疗提供新的思路。

霍乱弧菌是重要的肠道致病菌，严重威胁人类健康。肠道定植是其致病的前提，该过程由多种因子共同参与，但目前对这些因子功能的研究并不全面。申请人前期发现，缺失具有转录调控功能的蛋白SlmA后，霍乱弧菌的肠道定植能力显著下降，说明SlmA对霍乱弧菌的肠道定植有重要影响。以前对SlmA的研究主要集中在其对细菌二分裂的作用，而对该蛋白作用于肠道定植这一新功能的机制尚未明确。本项目首先通过小鼠体内RT-qPCR，发现slmA在肠道内的表达量明显高于体外；缺失slmA导致霍乱毒素的表达量显著降低，说明slmA可以通过影响霍乱毒素的合成进而影响其定植。ChIP-seq和EMSA实验表明，SlmA蛋白直接结合外膜蛋白编码基因ompU和毒素共调菌毛编码基因tcpA的启动子区域。DNA pull-down和EMSA实验确定slmA可能的上游调控蛋白VC0940。从而以slmA为出发点，丰富了霍乱弧菌的毒力调控网络，为霍乱的预防和治疗提供新的思路。