Enterococcal Pathogenesis:Role of Cytolysin

肠球菌发病机制：溶细胞素的作用

• 批准号: 9117371
• 负责人: Michael S Gilmore
• 金额: $ 41万
• 依托单位: MASSACHUSETTS EYE AND EAR INFIRMARY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-23 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9117371
• 关键词: Acute; Animal Model; Anti-Bacterial Agents; Antibiotics; Back; Bacteria; Binding; Blood Circulation; Caenorhabditis elegans; Cells; Cessation of life; Colon; Cytolysins; Cytoplasm; Elements; Enterococcus; Enterococcus faecalis; Eukaryotic Cell; Gastrointestinal tract structure; Genes; Genetic Transcription; Genome; Goals; Greater sac of peritoneum; Health; Hospitals; Human; Immune system; In Vitro; Infection; Insecta; Intercistronic Region; Intestinal Mucosa; Mammalian Cell; Maps; Mental Depression; Messenger RNA; Modeling; Multi-Drug Resistance; Mus; Nature; Nosocomial Infections; Nucleic Acid Regulatory Sequences; Operon; Organ; Organism; Pathogenesis; Pathogenicity; Pathogenicity Island; Pheromone; Process; Property; Public Health; Pump; Regulation; Repression; Risk; Role; Science; Severities; Signal Transduction; Site; Structure; Swelling; System; Time; Toxic effect; Toxin; Transcription Initiation Site; Virulence; Virulence Factors; Virulent; Work; bacteriocin; base; commensal microbes; genetic regulatory protein; in vivo; killings; lymph nodes; man; microbiota; novel; promoter; trafficking; trait

DESCRIPTION (provided by applicant): Enterococci have emerged as leading causes of multidrug resistant hospital infection. Yet they have existed as commensal microbes of everything from insects to man for over 400 million years. Our previous work, as well as the work of others, has shown that one of the factors that makes hospital isolate of Enterococcus faecalis more virulent is a toxin termed "cytolysin." The E. faecalis cytolysin has antibacterial properties, as well as being a cytolytic toxin for human cells. We previously showed that this toxin contributed a 5-fold increased risk of death from infection, that it was conveyed on a pathogenicity island along with several additional virulence traits, and that its expression is regulated by a novel process termed "telesensing" that allows the bacterium to detect the presence of target cells in the vicinity, and in respose produce high levels of the toxin. Although we have shown that the E. faecalis cytolysin toxi is novel in structure and regulation, we do not yet know how it contributes to the severity of infection in man, or in models of infection where it renders E. faecalis infection as much as 100 times more acutely toxic. We also do not know exactly how "telesensing" works at the level of transcription. Therefore, we propose to determine whether the antibacterial property of the toxin allows E. faecalis entry into the GI tract microbiota, whether it there causes changes in the bacterial composition and overgrows within the colon because of the antibacterial activity, whether it compromises the barrier function of the colon through its cytolytic activity for mammalian cells, or whether it exacerbates infection by impeding the innate immune system from clearing the organism from a site of infection. To understand how its expression is regulated, we also propose to dissect the novel two component regulatory system which has been shown to be necessary for its repression and depression. This will be done by mapping the precise points where transcription of the cytolysin operon is initiated, and determining the relationship between those start sites and structural features of the regulatory region of the operon. We will determine whether the inducing signal that results in high level toxin expression is communicated from the outside of the cell, or whether t is internalized and directly causes operon depression. Finally, we will determine exactl how each of the regulatory proteins relate to each other, and relate to structural features within the control region of the cytolysin operon. These results will provide needed information for knowing how the cytolysin exacerbates E. faecalis infection, as well as the information needed for controlling its expression.

描述（由申请人提供）：肠球菌已成为多重耐药性医院感染的主要原因。 然而，它们作为从昆虫到人类的一切生物的共生微生物已经存在了四亿多年。 我们之前的工作以及其他人的工作表明，使医院分离的粪肠球菌毒性更强的因素之一是一种称为“溶细胞素”的毒素。 粪肠球菌溶细胞素具有抗菌特性，也是人类细胞的溶细胞毒素。我们之前表明，这种毒素使感染死亡的风险增加了 5 倍，它与几个额外的毒力特征一起在致病岛上传播，并且它的表达受到一种称为“遥感”的新过程的调节，该过程允许细菌检测附近目标细胞的存在，并在休息时产生高水平的毒素。 尽管我们已经证明粪肠球菌溶细胞素毒素在结构和调节方面是新颖的，但我们还不知道它如何导致人类感染的严重程度，或者在感染模型中使粪肠球菌感染高达 100 毒性更剧烈。 我们也不知道“远程传感”到底是如何工作的 转录水平。因此，我们建议确定毒素的抗菌特性是否允许粪肠球菌进入胃肠道微生物群，是否会因抗菌活性而导致细菌组成发生变化并在结肠内过度生长，是否会通过其对哺乳动物细胞的细胞溶解活性损害结肠的屏障功能，或者是否会通过阻碍先天免疫系统来加剧感染 从感染部位清除微生物。为了了解其表达是如何受到调节的，我们还建议剖析新颖的两部分调节系统，该系统已被证明对其抑制和抑制是必要的。 这将通过绘制溶细胞素操纵子转录起始点的精确图谱，并确定这些起始位点与操纵子调节区的结构特征之间的关系来完成。我们将确定导致高水平毒素表达的诱导信号是否是从细胞外部传递的，或者是否是内化的并直接导致操纵子抑制。 最后，我们将准确确定每种调节蛋白如何相互关联，以及如何与溶细胞素操纵子控制区域内的结构特征相关。 这些结果将为了解溶细胞素如何加剧粪肠球菌感染以及 控制其表达所需的信息。