变异链球菌groE操纵子及其表达与调控

变异链球菌耐受口腔内多种环境的变化，主要依赖于多种热休克蛋白基因的表达。其中，groE操纵子表达的GroES-GroEL蛋白可辅助新合成的以及变性的蛋白质折叠、组装、转运和降解，从而影响细胞的代谢。变异链球菌groE操纵子位于1?834?692~1?832?649位点，包括σA型启动子、分子伴侣表达反向重复序列（CIRCE）、groES和groEL及终止子，在进化上高度保守，其表达受热、酸、乙醇和过氧化氢等多种应激环境的诱导，受CtsR和HrcA蛋白的双重负性调节。groE操纵子的调控有HrcA-CIRCE系统负调控假说和CtsR的负调控两种方式，但其具体调控机制尚未在变异链球菌中得到充分证实。从分子水平上研究变异链球菌groE操纵子的结构和调控机制，有助于进一步阐明细胞的生理过程，为了解细胞在应激和病变状态下的分子调节机制打下基础。

ThegroE operon ofStreptococcus mutans with its expression and regulation

Streptococcus mutans(S.mutans), as one of the primary cariogenic bacteria, can respond to several environmental stresses. This ability mainly depends on the translation and expression of variety of heat shock protein genes. groE operon, one of the best-studied heat shock genes, affects the metabolism of cells by translating the heat shock proteins, groES-groEL, which can mediate the folding, assembly, transport, and degradation of new or misfolding proteins. The groE operon locates in 1 834 692-1 832 649 sites, including a σA promoter, inverted repeat sequence(CIRCE), groES, groEL and a terminator. It is highly conserved, and can be induced to express by stress environment including heat, acid, ethanol and hydrogen peroxide. Both HrcA-CIRCE system and CtsR play a negative regulation role, without a clear mechanism. Studies, about the structure and regulation mechanism of S.mutans groE operon in a molecular level, help to further clarify the physiological process of cells, and lay the foundation for understanding the molecular mechanism of cells under stress and pathological conditions.