革兰氏阳性菌自然感受态生理机制的研究进展

Advances in Research on Natural Competence of Gram-positive Bacteria and Its Physiological Properties

自然感受态是指菌体在自然生长过程中吸附、摄取和内化外源DNA的生理状态。大部分细菌具有相似的DNA摄取机制,该机制主要由两部分组成:外源DNA在多种感受蛋白的共同作用下被核酸酶降解为单链DNA进入细胞,然后单链DNA在Dpr A、Ssb B和Rec A等蛋白的保护下整合到受体染色体上。目前对变形链球菌自然感受的调控系统研究较为广泛,拟以变形链球菌为例,结合其他细菌介绍自然感受的研究进展。Com X是变形链球菌的感受核心调控因子,可以激活多种后期感受基因的转录,这些后期感受基因对外源DNA的摄取发挥着重要作用。以变形链球菌的com X为核心,梳理总结了Com DE、ComRS、HdrRM、BsrRM和RcrRPQ等系统对com X的调控机理,分析了Com X稳定性及其对后期感受基因的调控,阐述了自然感受与生物膜形成、耐酸性和细菌素合成等毒力因子的内在联系,在此基础上展望了自然感受未来可能的研究方向。

Natural competence is a physiological state in which bacteria develop a capacity to take up exogenous DNA in the natural environment. Most bacteria have similar DNA-uptake mechanism which mainly includes two processes. Firstly the exogenous DNA is degraded into single-stranded DNA（ ss DNA） with the coordinated effect of competence protein. Then ss DNA are integrated into the chromosome under the protection of Dpr A,Ssb B and Rec A. Nowadays,the competence regulation in Streptococcus mutans is extensively studied. S.mutans combined with other bacteria were cited as the examples to introduce the advances of natural competence.The ComX in S. mutans works as a core regulatory protein during natural competence. It could activate a large set of late competence genes required for exogenous DNA uptake and integration. The comX in S. mutans are focused on. The regulatory mechanisms of Com DE,ComRS,HdrRM,BsrRM and RcrRPQ on comX were summarized. Besides,ComX stability and ComX-regulated genes were elucidated. Meanwhile,the intimate linkage between natural competence and biofilm formation,acid resistance as well as bacteriocins synthesis was analyzed. Finally,the potential research trends of natural competence were put forward.