Regulation of cytolysin production in Enterococcus feacalis

描述（由申请方提供）：粪肠球菌是人类肠道植物群的常见宿主，也是人类感染的常见原因。在过去的几十年里，肠球菌由于其在住院患者中引起致命感染的能力以及其容易将毒力决定因素（例如抗生素抗性）转移到其他微生物的能力而变得突出。这种微生物在环境中持续存在的能力，定殖各种宿主，并将毒力传递给其他病原体，使得阐明这种细菌的毒力机制势在必行。一个这样的因子，已被公认为是其贡献的毒力的E。粪便是毒素溶细胞素细胞溶解素是一种新型毒素，能够溶解多种细胞类型和生物体-细菌和真核生物。溶细胞素毒素由两个亚基CylLL和CylLs组成，这两个亚基都被广泛修饰以产生其活性形式。两种独特的调节蛋白CylR 1和CylR 2对于控制毒素表达是必需的。使该系统不寻常的是，CylR 1和CylR 2与其他细菌系统中的已知调节组分没有显著的同源性，并且通过未知的机制起作用以使溶细胞素操纵子的转录失效。此外，毒素亚基之一，CylLs，已显示诱导溶细胞素的产生。溶细胞素毒素是大肠杆菌的重要毒力因子。粪肠球菌，并且受到独特的调节机制的影响，因此有兴趣了解这种毒素是如何被调节的，以希望改进治疗措施来破坏这种生物体的感染。因此，本申请旨在鉴定CylR 1和CylR 2调节溶细胞素表达的机制，并确定CylLs在该调节过程中的作用。为了实现这些目标，我们将检查CylR 1和CylR 2的细胞定位，评估它们相互作用和与CylLs相互作用的能力，并研究这些相互作用对溶细胞素操纵子调节的影响。

DESCRIPTION (provided by applicant): Enterococcus faecalis is a common resident of human intestinal flora and a frequent cause of infection in humans. Enterococci have grown in prominence over the past few decades due to their ability to cause fatal infections in hospitalized persons and their capacity to readily transfer virulence determinants, such as antibiotic resistances, to other microbes. The ability of this organism to persist in the environment, colonize a variety of hosts, and pass virulence capabilities to other pathogens makes elucidation of virulence mechanisms in this bacterium imperative. One such factor that has been recognized for its contribution to the virulence of E. faecalis is the toxin, cytolysin. Cytolysin is a novel toxin, capable of lysing a wide variety of cell types and organisms - both bacterial and eukaryotic. The cytolysin toxin consists of two subunits, CylLL and CylLs, both of which are extensively modified to generate their active forms. Two unique regulatory proteins, CylR1 and CylR2, are essential for controlling toxin expression. What makes this system unusual is that CylR1 and CylR2 bear no significant homology to known regulatory components in other bacterial systems, and function by an unknown mechanism to disable transcription of the cytolysin operon. Furthermore, one of the toxin subunits, CylLs, has been shown to induce cytolysin production. As cytolysin toxin is both a significant virulence factor of E. faecalis, and is subject to unique regulatory mechanisms, it is of interest to understand how this toxin is regulated in hopes of improving therapeutic measures to subvert infections by this organism. Therefore, this application aims to identify the mechanisms by which CylR1 and CylR2 regulate expression of cytolysin and to determine the role of CylLs in this regulatory process. To achieve these aims, we will examine the cellular localization of both CylR1 and CylR2, assess their ability to interact with each other and CylLs, and study the effects of these interactions on the regulation of the cytolysin operon.