Regulation of Streptococcus mutans Virulence by covR/S

描述（由申请人提供）：在感染过程中，致病菌广泛使用双组分信号转导系统来调节其毒力因子的表达，以响应不断变化的环境线索。变形链球菌暴露于人类口腔的短暂环境中，在那里它是龋齿的主要病因。具体来说，pH值、氧含量和养分有效性的变化可能需要快速的细菌反应来促进变形链球菌诱导的龋齿发生。我们在变形链球菌中发现了一个与a群链球菌（GAS）的covR/S双组分信号转导系统同源的基因对。已知CovR/S可调控与GAS毒力相关的多个基因的表达，包括胶囊生产所必需的basal基因和编码纤溶酶原激活物的ska基因。在实验室进行的研究表明，变形链球菌在调节果糖基转移酶（ftf）中的同源物覆盖vr /S，而果糖基转移酶介导了细菌粘附在牙膜上所必需的果糖的蔗糖依赖性生产。由于变形链球菌产生多种促进其在人类宿主中存活和持续存在的因子，我们假设CovR/ s可能作为变形链球菌基因的全球调节剂，其产物促进口腔疾病。本研究申请的主要目的是确定CovR/S在突变链球菌毒力控制中的假定作用。具体目标包括：1。最近在实验室构建的一株变异链球菌covR-突变体的鉴定及其在无菌大鼠中的致龋性分析2. 利用差分显示聚合酶链反应（ddPCR）和二维蛋白质组学方法鉴定在近似口腔的环境中受CovR/ s控制的变形链球菌基因；3. 构建突变链球菌敲除突变体和报告基因融合体，对CovR/ s调控基因进行功能表征并分析其表达。总的来说，这些研究将阐明变形链球菌毒力基因控制的机制，从而能够预防和/或干预导致龋齿发展的致病过程。

DESCRIPTION (provided by applicant): Two component signal transduction systems are widely used by pathogenic bacteria to regulate the expression of their virulence factors in response to changing environmental cues during the infectious process. Streptococcus mutans is exposed to the transient environments of the human oral cavity where it is the primary etiologic agent of Dental caries. Specifically, changes in pH, oxygen content, and nutrient availability are likely to necessitate a rapid bacterial response to promote S. mutans-induced cariogenesis. We identified a gene pair in S. mutans that is homologous to the covR/S two-component signal transduction system in the group A streptococci (GAS). CovR/S is known to regulate the expression of multiple genes associated with GAS virulence, including basal which is necessary for capsule production and ska, which encodes a plasminogen activator. Work conducted in5laboratory implicates the S. mutans covR/S homologs in the regulation of fructosyltransferases (ftf) that mediate the sucrose-dependent production of fructans necessary for bacterial adherence to the tooth pellicle. Since S. mutans produces a multitude of factors that promote its survival and persistence in the human host, we posit that CovR/Smay function as a global regulator of S. mutans genes whose products promote disease in the oral cavity. The major goal of this research application is to define a putative role for CovR/S in S. mutans virulence control. The Specific Aims include: 1. Characterization of a S. mutans covR- mutant recently constructed in5laboratory, and analysis of its cariogenic potential in germfree rats; 2. Identification of the S. mutans gene(s) that are subject to CovR/S control in environments that approximate the oral cavity using differential display polymerase chain reaction (ddPCR) and 2D proteomic approaches; 3. construction of S. mutans knockout mutants and reporter gene fusions to functionally characterize CovR/S-regulated genes and analyze their expression. Taken collectively, these studies will elucidate S. mutans mechanism(s) of virulence gene control, and so enable prevention and/or intervention in the pathogenic process that leads to the development of Dental caries.