Peptide Pheromones in Enterococcal Plasmid Maintenance

描述（由申请人提供）：粪肠球菌在当前的抗生素耐药性危机中起着重要作用。它是抗生素耐药医院感染的主要原因之一，并且作为肠道正常菌群的一部分，也可作为抗生素耐药基因的储存库。肽信息素诱导的共轭质粒转移有助于这些抗生素抗性基因和其他肠球菌毒力因子的传播。本研究的重点是肽信号在质粒维持中的作用，特别是在粪肠球菌中四环素耐药质粒pCF10。在共轭质粒生物学中对信息素信号的初步观察发现，无质粒受体细胞产生的肽信号cCF10被用于诱导共轭pCF10的转移。cCF10在细胞表面产生，并通过cCF10受体与寡肽渗透酶的相互作用被含有pcf10的供体细胞内化。一旦进入细胞，cCF10与细胞内效应分子相互作用诱导偶联。最近，我们发现供细胞产生的cCF10在维持粪肠球菌细胞群中pCF10的第二个作用。在供体细胞群体中，cCF10也被产生，并且需要其内化来维持pCF10在明显没有偶联的情况下。维持功能发生在不能共轭转移的最小pCF10复制子结构中，这表明cCF10在pCF10维持中的作用与其在共轭转移中的作用不同。

DESCRIPTION (provided by applicant): Enterococcus faecalis plays a major role in the current antibiotic resistance crisis. It is one of the leading causes of antibiotic-resistant nosocomial infections and, as part of the normal flora of the intestinal tract, also serves as a reservoir of antibiotic resistance genes. Peptide pheromone-induced conjugative plasmid transfer contributes to the spread of these antibiotic resistance genes and of other enterococcal virulence factors. The focus of this research is on the role of peptide signaling in plasmid maintenance, specifically of the tetracycline-resistance plasmid pCF10 in Enterococcus faecalis. The original observations of pheromone signaling in conjugative plasmid biology found that the peptide signal cCF10 produced by plasmid-free recipient cells is used for the induction of conjugative pCF10 transfer. cCF10 is produced at the cell surface and internalized by pCF10-containing donor cells by interaction of the cCF10 receptor with the oligopeptide permease. Once inside the cell cCF10 interacts with intracellular effector molecules to induce conjugation. Recently, we have found a second role, for donor-cell produced cCF10, in maintaining pCF10 in the Enterococcus faecalis cell population. In a donor cell population, cCF10 is also produced and its internalization is required to maintain pCF10 in the apparent absence of conjugation. The maintenance functions occur with a minimum pCF10 replicon construct that is unable to be conjugatively transferred, suggesting the role of cCF10 in pCF10 maintenance is distinct from its role in conjugative transfer. The main goal of the research proposed in this application is to gain a basic understanding of how cCF10 is affecting pCF10 maintenance. (1) Does cCF10 act as a pheromone in maintenance of pCF10? (2) Are the oligopeptide permease and the cCF10 receptor PrgZ required for efficient transport of cCF10 (produced extracellularly)? (3) What are the basic features of the pCF1 0 replicon? (4) What are the intracellular effector molecules responsible for cCF10-dependent pCF10 maintenance? This will lay the groundwork for future experiments to determine how the same peptide can be used for plasmid maintenance without inducing detectable levels of conjugation.