Ji G, Beavis R C, Novick R P
Molecular Pathogenesis Program, Skirball Institute of Biomolecular Medicine, New York University Medical Center, New York 10016, USA.
Proc Natl Acad Sci U S A. 1995 Dec 19;92(26):12055-9. doi: 10.1073/pnas.92.26.12055.
Some bacterial pathogens elaborate and secrete virulence factors in response to environmental signals, others in response to a specific host product, and still others in response to no discernible cue. In this study, we have demonstrated that the synthesis of Staphylococcus aureus virulence factors is controlled by a density-sensing system that utilizes an octapeptide produced by the organism itself. The octapeptide activates expression of the agr locus, a global regulator of the virulence response. This response involves the reciprocal regulation of genes encoding surface proteins and those encoding secreted virulence factors. As cells enter the postexponential phase, surface protein genes are repressed by agr and secretory protein genes are subsequently activated. The intracellular agr effector is a regulatory RNA, RNAIII, whose transcription is activated by an agr-encoded signal transduction system for which the octapeptide is the ligand.
一些细菌病原体根据环境信号合成并分泌毒力因子，另一些则对特定的宿主产物作出反应，还有一些对无法识别的信号作出反应。在本研究中，我们证明了金黄色葡萄球菌毒力因子的合成受一种密度感应系统控制，该系统利用细菌自身产生的八肽。这种八肽可激活agr位点的表达，agr位点是毒力反应的全局调节因子。这种反应涉及编码表面蛋白的基因与编码分泌型毒力因子的基因之间的相互调节。当细胞进入指数后期时，表面蛋白基因被agr抑制，随后分泌蛋白基因被激活。细胞内的agr效应物是一种调节性RNA，即RNAIII，其转录由agr编码的信号转导系统激活，八肽是该信号转导系统的配体。
