SrrAB-VraSR协同调控表皮葡萄球菌生物膜形成及PCD的分子机制

表皮葡萄球菌生物膜引起的持续性感染目前尚无有效治疗药物。双组分信号转导系统（TCS）能感应环境中压力因子的变化，调控细菌的多种生物学功能。前期发现TCS-SrrAB通过ica途径调控表皮葡萄球菌生物膜形成，但与药物敏感性无直接关系，而敲除TCS-VraSR后表皮葡萄球菌生物膜形成能力降低，生物膜内死细菌数显著增多，抗压能力下降，转录组测序提示VraSR负调节Cid/Lrg系统来介导表皮葡萄球菌的存活（PCD），并且磷酸化VraR蛋白能与ica启动区结合，提示SrrAB与VraSR存在协同作用。后续将构建SrrAB-VraSR双突变株，互补株，过表达株，结合转录组测序筛选可能受SrrAB/VraSR调控的下游靶基因，并用凝胶阻滞试验、启动子融合技术和染色质免疫共沉等进行验证，探索SrrAB/VraSR协同调控表皮葡萄球菌生物膜形成及PCD的分子机制，为研究抗细菌生物膜药物靶点奠定基础。

At present, no effective antibiotics can be used to kill the bacteria within biofilm formed by Staphylococcus epidermidis. The two-component regulatory system (TCS) is capable of rapidly sensing environmental stimuli and controlling multi-biological activities in bacteria. Previous study has found that TCS-SrrAB, having little relationship with drug tolerance, regulates biofilm formation in ica-dependent pathway. However, deletion of TCS-VraSR resulted in decreased biofilm formation, more dead cells within biofilm significantly, and decreased tolerance against environmental stressor, and phosphorylated VraR can bind with promoter region of ica operon. The above data indicated that SrrAB cooperating with VraSR regulate the biofilm formation and bacterial programmed cell death (PCD). Then further study on phenotypic changes will be performed after construction of △SrrAB-VraSR mutant, complementary strain and over-express strain. RNA Seq will be used to analyze expression level of genes involved in phenotype change, and the suspected ones regulated by SrrAB/VraSR will be confirmed by electrophoretic mobility shift assay (EMSA), lacZ reporter plasmid, Chromatin immunoprecipitation (ChIP), and DNase I footprinting. It lays a theoretical foundation for the study on drugs against bacterial biofilm infection.