Characterization of ComC export and processing in Streptococcus sanguinis

血链球菌 ComC 输出和加工的特征

• 批准号: 8020940
• 负责人: Jill E Callahan
• 金额: $ 1.39万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-25 至 2011-05-24
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8020940
• 关键词: Animal Model; Bacteria; Cardiac; Cleaved cell; Collection; Coma; Competence; DNA; Dental Plaque; Endocarditis; Ensure; Environment; Genes; Genetic; Glycine; Growth; Heart Valves; Infection; Infective endocarditis; Microbial Biofilms; Modeling; Oral; Oral cavity; Oral health; Orthologous Gene; Peptide Hydrolases; Peptides; Phenotype; Play; Process; Property; Proteins; Regulator Genes; Regulon; Research; Role; Screening procedure; Signal Transduction; Signaling Molecule; Site; Streptococcus; Streptococcus Viridans Group; Streptococcus gordonii; Streptococcus mutans; Streptococcus pneumoniae; System; Virulence; base; fitness; interest; member; mutant; protein aminoacid sequence; public health relevance; quorum sensing; tooth surface; uptake

DESCRIPTION (provided by applicant): Streptococcus sanguinis is a member of the viridans streptococci and is among the earliest colonizers of the dental plaque biofilm on the tooth surface. Within this niche, S. sanguinis is believed to play a beneficial role by competing with the growth of harmful bacteria in the mouth. However, S. sanguinis is also a leading cause of infective endocarditis, an often lethal infection of the cardiac valves. This research aims to identify genes that contribute to fitness in both the oral and cardiac environments. In this regard, we have recently begun to characterize the S. sanguinis com regulon. The most apparent function of this regulon is genetic competence- the ability to incorporate free, exogenous DNA from the environment. Based on previous studies in Streptococcus pneumoniae and Streptococcus mutans, we hypothesized that the com regulon might also be important for endocarditis virulence or biofilm formation. Our preliminary results suggest that the com regulon does not enhance endocarditis virulence; however it appears to have a significant effect on biofilm formation. Such findings suggest that this regulon may be an important determinant of competitiveness in the mouth. A model of the competence regulon in S. sanguinis is being constructed based on the well characterized system of Streptococcus pneumoniae. In S. pneumoniae, the competence inducing precursor peptide, ComC, is cleaved to its active form, competence stimulating peptide (CSP), and secreted to serve as a quorum sensing signal, inducing DNA uptake. Cleavage occurs at a conserved site through the activity of ComA, an ABC exporter with peptidase activity. Our results suggest S. sanguinis ComC is also processed and secreted as CSP. However, the conserved cleavage site is lacking in S. sanguinis ComC and no ComA ortholog or other protein capable of processing ComC has been identified. Despite our progress, many features of S. sanguinis com regulon induction are not understood. To further characterize such fundamental aspects of this important system with S. sanguinis we propose three aims: (1) to isolate and determine the sequence of secreted competence stimulating peptide (CSP) (2) to identify the S. sanguinis ComC export and processing system by screening a collection of defined mutants (3) to examine export and processing of S. sanguinis ComC in a heterologous host. Together, these aims provide a range of approaches for characterization of a system that may contribute in multiple ways to the competitiveness of S. sanguinis within the mouth. Once this system is better characterized, our findings may allow manipulation of the com system to enhance favorable properties of S. sanguinis in the mouth without enhancing its virulence for endocarditis. Public Health Relevance: The bacterium Streptococcus sanguinis is an important component of dental plaque and may benefit people by competing against harmful bacteria in the mouth. We are characterizing a system in Streptococcus sanguinis that enables it to take up DNA from its surroundings and may also help it survive in the mouth. This study proposes to characterize the most fundamental components of this important system.

描述(申请人提供)：血链球菌是绿色链球菌的一员，是牙面菌斑生物膜最早的定殖者之一。在这一生态位中，血链球菌被认为通过与口腔中有害细菌的生长竞争而发挥有益的作用。然而，血链球菌也是感染性心内膜炎的主要原因，感染性心内膜炎通常是一种致命的心脏瓣膜感染。这项研究旨在确定在口腔和心脏环境中对健康有贡献的基因。在这方面，我们最近开始描述血链球菌的调节子。这个调节子最明显的功能是遗传能力--从环境中结合游离的外源DNA的能力。基于先前对肺炎链球菌和变形链球菌的研究，我们推测COM调节子也可能对心内膜炎的毒力或生物被膜的形成起重要作用。我们的初步结果表明，COM调节子不会增强心内膜炎的毒力；但它似乎对生物被膜的形成有显着影响。这些发现表明，这种调节可能是口腔竞争力的一个重要决定因素。根据肺炎链球菌的特征系统，正在构建血链球菌能力调节蛋白的模型。在肺炎链球菌中，能力诱导前体多肽Comc被切割成其活性形式能力刺激多肽(CSP)，并被分泌作为群体感应信号，诱导DNA摄取。切割发生在一个保守的位置上，通过具有肽酶活性的ABC出口蛋白Coma的活性进行。我们的结果表明，血链球菌也被加工和分泌为CSP。然而，在血链球菌中缺乏保守的裂解位点，也没有鉴定出COMA同源物或其他能够处理Comc的蛋白质。尽管我们取得了进展，但血链球菌调控子诱导的许多特征仍不清楚。为了进一步研究血链球菌这一重要系统的基本特征，我们提出了三个目标：(1)分离和测定分泌型能力刺激肽(CSP)的序列；(2)通过筛选一组已定义的突变体来鉴定血链霉菌的出口和加工系统；(3)研究血链球菌在异源宿主中的出口和加工。总而言之，这些目标提供了一系列方法来描述一个系统，该系统可能以多种方式有助于口腔内血链球菌的竞争力。一旦这个系统有了更好的特征，我们的发现可能允许操纵COM系统来增强口腔中血链球菌的良好特性，而不会增强其对心内膜炎的毒力。 公共卫生相关性：血链球菌是牙菌斑的重要组成部分，可能通过与口腔中的有害细菌竞争而使人们受益。我们正在描述血链球菌的一种系统，该系统使它能够从周围环境中吸收DNA，并可能帮助它在口腔中生存。这项研究建议描述这一重要系统的最基本组成部分。