Regulation of cytolysin production in Enterococcus feacalis

粪肠球菌溶细胞素产生的调节

• 批准号: 7485293
• 负责人: SHONNA M. MCBRIDE
• 金额: $ 4.96万
• 依托单位: SCHEPENS EYE RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7485293
• 关键词: Antibiotic Resistance; Bacteria; Binding; Biochemical; Cells; Clinical; Co-Immunoprecipitations; Coupled; Cytolysins; Cytolysis; DNA Binding; Enterococcus; Enterococcus faecalis; Environment; Gastrointestinal tract structure; Genes; Genetic; Genetic Transcription; Goals; Helix-Turn-Helix Motifs; Human; Infection; Intestines; Life; Measures; Microbe; Molecular; Operon; Organism; Pattern; Persons; Process; Production; Protein Binding; Regulation; Repression; Research Personnel; Role; Signal Transduction; System; Testing; Therapeutic; Toxin; Ursidae Family; Virulence; Virulence Factors; cell type; genetic regulatory protein; improved; interest; novel; pathogen; perforin; promoter; response; sensor; sensor histidine kinase

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.

描述（由申请人提供）：粪肠球菌是人类肠道菌群的常见居民，也是人类感染的常见原因。肠球菌在过去几十年中变得越来越重要，因为它们能够引起住院患者致命的感染，并且能够轻易地将抗生素耐药性等毒力决定因素转移给其他微生物。这种生物体能够在环境中持续存在、在多种宿主中定植并将毒力能力传递给其他病原体，这使得阐明这种细菌的毒力机制势在必行。一种已被认为对粪肠球菌毒力有贡献的因素是毒素，即溶细胞素。溶细胞素是一种新型毒素，能够裂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，这两个亚基都经过广泛修饰以产生其活性形式。两种独特的调节蛋白 CylR1 和 CylR2 对于控制毒素表达至关重要。该系统的不同寻常之处在于，CylR1 和 CylR2 与其他细菌系统中已知的调节成分没有显着的同源性，并且通过未知的机制发挥作用，使溶细胞素操纵子的转录失效。此外，毒素亚基之一 CylLs 已被证明可以诱导溶细胞素的产生。由于溶细胞素毒素既是粪肠球菌的重要毒力因子，又受到独特的调节机制的影响，因此有必要了解这种毒素是如何调节的，以期改进治疗措施以颠覆该生物体的感染。因此，本申请旨在确定 CylR1 和 CylR2 调节溶细胞素表达的机制，并确定 CylL 在此调节过程中的作用。为了实现这些目标，我们将检查 CylR1 和 CylR2 的细胞定位，评估它们彼此以及 CylL 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。