Oral streptococcal-enterococcal peptide-mediated intercellular communication

描述（由申请方提供）：戈登链球菌是人类口腔中的一种重要细菌，可能与牙源性感染以及感染性心内膜炎相关。粪肠球菌主要是肠道微生物菌群的组成部分，已成为一种机会致病菌，已知携带编码临床显著毒力因子和抗生素耐药性的多种质粒。E.粪便也存在于口腔中，并且在牙髓感染中具有特别重要的意义，在牙髓感染中，粪便通常从牙髓治疗失败和持续感染的牙髓管中回收。移动的DNA元件在S. gordonii和E.已经在体外和离体牙齿模型中证明了粪链球菌的存在。由于这两种微生物都存在于口腔中，并且已经从牙髓感染中恢复，因此这种DNA转移有可能在体内发生。E.粪球菌分泌多个七聚体和八聚体肽信息素，其在携带接合质粒的特定家族的肠球菌中诱导交配反应。所述肽在携带质粒的应答细胞中诱导凝集/交配反应，涉及参与细胞间聚集和DNA转移功能的细胞表面蛋白的表达，从而促进细胞间接触和质粒转移。这一过程在携带质粒的肠球菌供体和无质粒的肠球菌受体之间得到了充分的研究。质粒pAM 373是肠球菌接合质粒，其响应于从无质粒肠球菌分泌的其同源信息素cAM 373。携带对多种抗生素（包括万古霉素）的抗性的pAM 373衍生物也是cAM 373响应性的。质粒pAM 373是新的，因为它也响应来自S. gordonii。我们最近发现了编码S. gordonii七肽gordonii-cAM 373。合成的gordonii-cAM 373能够在E. faecalis的质粒转移，并诱导E. faecalis到S. gordonii。这是第一次证明来自链球菌的肽可以作为E。faecalis交配信号并促进属间质粒转移。这些结果对链球菌信息素样肽在属间DNA转移中的潜在作用具有有趣的意义，并表明这些肽可以提供信号，通过这些信号，E。粪肠球菌可能有助于水库的毒力和抗性决定因素在口腔植物群。相反，链球菌信号诱导E.粪肠球菌推定的毒力因子表明，在多种微生物感染中口腔链球菌的存在可能会增加大肠杆菌的致病潜力。粪便我们拟通过以下具体目的进一步研究这种新的属间细胞间通讯：1）进一步表征S. gordonii camG基因的表达和加工，并确定有利于或不利于其表达的环境条件;粪链球菌毒力基因的表达。gordonii信息素产生细胞和gordonii-cAM 373肽。

DESCRIPTION (provided by applicant): Streptococcus gordonii, a prominent commensal bacterium of the human oral cavity, can be associated with odontogenic infections as well as infective endocarditis. Enterococcus faecalis, predominantly a component of gut microflora, has emerged as an opportunistic pathogen, known to carry multiple plasmids encoding clinically significant virulence factors and antibiotic resistance. E. faecalis is also found in the oral cavity and is of particular significance in endodontic infections where it is commonly recovered from pulp canals with failed endodontic treatment and persistent infection. Transfer of mobile DNA elements between S. gordonii and E. faecalis has been demonstrated in vitro and in an ex vivo tooth model. Since both organisms inhabit the oral cavity and have been recovered from recalcitrant endodontic infections, such DNA transfer has the potential to occur in vivo. E. faecalis secretes multiple hepta- and octameric peptide pheromones that induce a mating response in enterococci harboring specific families of conjugative plasmids. The peptides induce a clumping/mating response in plasmid-carrying responder cells, involving expression of cell-surface proteins involved in inter-cellular aggregation and DNA transfer functions, thereby facilitating inter-cellular contact and plasmid transfer. This process is well-studied between plasmid-bearing enterococcal donors and plasmid-free enterococcal recipients. Plasmid pAM373 is an enterococcal conjugative plasmid that responds to its cognate pheromone cAM373 secreted from plasmid-free enterococci. Derivatives of pAM373 that carry resistance to multiple antibiotics including a vancomycin, are also cAM373-responsive. Plasmid pAM373 is novel in that it also responds to pheromone-like signals from S. gordonii. We have recently identified the gene, camG, that encodes the S. gordonii heptapeptide gordonii-cAM373. Synthetic gordonii-cAM373 was able to induce a clumping response in E. faecalis and induce plasmid transfer from E. faecalis to S. gordonii. This is the first demonstration that a peptide from a streptococcal species can act as an E. faecalis mating signal and facilitate intergeneric plasmid transfer. These results have intriguing implications for a potential role of streptococcal pheromone-like peptides in intergeneric DNA transfer, and suggest that such peptides could provide signals by which E. faecalis could contribute to the reservoir of virulence and resistance determinants in the commensal oral flora. Conversely, this demonstration of a streptococcal signal that induces expression of E. faecalis putative virulence factors suggests that the presence of oral streptococci in polymicrobial infections may increase the pathogenic potential of E. faecalis. We propose to further investigate this novel intergeneric cell-to-cell communication via the following Specific Aims: 1) to further characterize the molecular mechanisms involved in S. gordonii camG expression and processing and determine environmental conditions that favor or disfavor its expression; 2) To monitor the response of E. faecalis virulence genes when exposed to S. gordonii pheromone-producing cells and gordonii-cAM373 peptide.