Genetic Functions of an Enterococcal R Factor

描述(申请人提供)：细菌病原体中抗生素耐药性的增加，加上新抗菌剂引入速度的持续下降，构成了现代医学中最严重的问题之一。根据这项拨款开展的研究涉及对粪肠球菌中已知的耐药性决定因素快速传播的最有效系统的研究，粪肠球菌是导致革兰氏阳性细菌病原体出现耐药性的最重要因素。本研究的重点是无质粒细胞产生的一种小肽信息素诱导携带抗生素耐药质粒pCF10的供体细胞将该质粒的拷贝转移到受体的分子和遗传学基础。这种细胞间通信的形式非常复杂、具体和高效。在这项申请中提出的研究将集中在参与控制信息素反应的几个关键成分，以及它们如何在分子水平上发挥作用。具体目标如下：1.阐明信息素与信息素受体蛋白PRGX结合诱导结合功能的分子机制。2.确定pCF10编码的Qa调控RNA抑制信息素诱导的结合转移操纵子转录延伸的机制。3.确定PrgY的作用机制，PrgY是一种新型的膜蛋白，作用于细胞表面，防止内源产生的细胞相关信息素对供体细胞的自我诱导。

DESCRIPTION (provided by applicant): The increasing incidence of antibiotic resistance in bacterial pathogens, coupled with a continuing decrease in the rate of introduction of new antimicrobial agents, constitutes one of the most serious problems in modern Medicine. The research carried out under this grant involves the study of the most efficient system for rapid dissemination of resistance determinants known in the bacterium Enterococcus faecalis, a species which is the most important contributor to the emergence of resistance in gram positive bacterial pathogens. This research is focused on the molecular and genetic basis for the ability of a small peptide pheromone produced by plasmid-free cells to induce donor cells carrying the antibiotic resistance plasmid pCF10 to transfer a copy of the plasmid to a recipient. This form of cell-cell communication is highly complex, specific, and efficient. The research proposed in this application will focus on several of the key components involved in control of the pheromone response, and how they function at the molecular level. The specific aims are as follows: 1. Elucidate the molecular mechanism by which pheromone binding to the pheromone receptor protein PrgX leads to induction of conjugation functions. 2. Determine the mechanism by which the pCF10-encoded Qa regulatory RNA inhibits extension of transcription of the pheromone-inducible conjugative transfer operon. 3. Determine the mechanism of action of PrgY, a novel membrane protein that acts at the cell surface to prevent self-induction in donor cells by endogenously produced, cell-associated pheromone.