Genetic and biochemical studies of competence regulation by the hdrRM operon

描述（由申请人提供）：拟定研究旨在研究新发现的高细胞密度响应性hdrRM操纵子在变形链球菌中的感受态调节的遗传和生化机制。本课题的主要目的是：1）确定hdrRM调控的感受态级联反应步骤; 2）确定HdrRM的基因调控机制。1)为了分析hdrRM操纵子如何与感受态级联的基因相互作用，将进行转录、上位性和突变分析的组合。这些研究将为hdrRM作为能力负调节因子的作用提供遗传基础。2)为了表征HdrR作为感受态调节剂的机制，HdrR将用于感受态基因启动子的DNA结合测定。此外，HdrR和HdrM之间的体内蛋白质相互作用研究将表征两种蛋白质之间可能的相互作用。这些数据有望为Aim 1中产生的遗传和转录数据提供生化证据，并确定HdrRM系统中的信号转导机制。本项目的目标是使用感受态调节作为模型的机制，通过该机制，hdrRM操纵子能够调节变形链球菌的其他重要毒力因子。由于这种操纵子是由高细胞密度的条件下强烈诱导，预计它将在牙菌斑的高细胞密度环境中的存活和致病性中发挥关键作用。 项目叙述：龋齿是人类最常见的细菌性疾病，在很大程度上与变形链球菌的过度生长有关。由于其致病能力要求其在牙菌斑的高细胞密度条件下发挥作用，因此对在高细胞密度条件下发挥作用的基因调节剂的研究可能会产生新的治疗策略来控制S.变种人

DESCRIPTION (provided by applicant): The proposed research Aims to investigate the genetic and biochemical mechanisms of competence regulation in Streptococcus mutans by the newly discovered high cell density responsive hdrRM operon. The goals of this project will be achieved in two Aims by: 1) Determining the steps of the competence cascade that are regulated by hdrRM 2) Determining the mechanism of gene regulation by HdrRM. 1) To analyze how the hdrRM operon interacts with the genes of the competence cascade, a combination of transcription, epistatic, and mutation analysis will be performed. These studies will provide the genetic basis for the role of hdrRM as a negative regulator of competence. 2) To characterize the mechanism of HdrR as a regulator of competence, HdrR will be used for DNA binding assays of competence gene promoters. In addition, in vivo protein interaction studies between HdrR and HdrM will characterize possible interactions between the two proteins. These data are expected to provide biochemical evidence for the genetic and transcriptional data generated in Aim 1 as well as determine the mechanism of signal transduction in the HdrRM system. The goal of this project is to use competence regulation as a model for the mechanism by which the hdrRM operon is able to regulate other important virulence factors of Streptococcus mutans. Since this operon is strongly induced by conditions of high cell density, it is expected that it will play a crucial role for both survival and pathogenicity in the high cell density environment of the dental plaque. Project Narrative: Dental caries is the most common human bacterial disease and is largely correlated with the overgrowth of Streptococcus mutans. Since its ability to cause disease requires it to function in the high cell density conditions of dental plaque, studies of gene regulators that function in high cell density conditions may yield novel treatment strategies to control the pathogenesis of S. mutans.