The irvA-dependent pathway: a link between stress adaptation and virulence

项目描述（由申请人提供）：拟开展的研究旨在通过irva依赖途径研究变形链球菌基因调控的遗传和生化机制。本项目的目标将通过以下三个方面来实现：1)分析irvA诱导的机制；2)鉴定irvA调控；3)表征构成irvA依赖途径的遗传调控因子。1)为了分析irvA诱导的机制，我们将对SMu1275的关键残基进行详细的生化研究，以确定其内源性自裂能力如何调节其控制irvA表达的能力。2)为了确定IrvA调控子，我们将采用染色质免疫沉淀和芯片技术（ChIP-chip）。使用特殊设计的Affymetrix基因芯片(R)，我们将能够检测体内大部分或全部IrvA结合位点。这些基因的转录分析将确定IrvA作为与应激和毒力相关表型相关基因的转录调节因子的作用。3)为了表征irvA依赖通路的遗传调控因子，我们将首先确定能够诱导irvA的基因。遗传分析将检查irvA在这些菌株中作为应激和毒力相关表型的中介的作用。最后，将确定与irva依赖性途径共调控的基因。本项目的目的是利用irva依赖通路作为模型，研究变形链球菌的应激适应与重要毒力因子调控之间的联系。由于变形链球菌的长期存在需要应激反应机制和毒力因子基因表达的协调，这些数据可能为变形链球菌的致癌性提供新的见解。

DESCRIPTION (provided by applicant): The proposed research aims to investigate the genetic and biochemical mechanisms of gene regulation in Streptococcus mutans through the irvA-dependent pathway. The goals of this project will be achieved in three aims by: 1) Analyzing the mechanism of irvA induction 2) Identifying the IrvA regulon 3) Characterizing the genetic regulators that comprise the irvA-dependent pathway. 1) To analyze the mechanism of irvA induction, we will perform detailed biochemical studies of key residues of SMu1275 to determine how its endogenous autocleavage capacity can modulate its ability to control irvA expression. 2) To identify the IrvA regulon, we will employ chromatin immunoprecipitation and microarray (ChIP-chip). Using specially designed Affymetrix Genechips(R), we will be able to detect most or all of the IrvA binding sites in vivo. Transcription analysis of these genes will determine the role of IrvA as a transcription regulator of genes associated with stress and virulence related phenotypes. 3) To characterize the genetic regulators of the irvA-dependent pathway, we will first identify the genes that are capable of inducing irvA. Genetic analyses will then examine the role of irvA as a mediator of stress and virulence related phenotypes in these strains. Finally, genes coregulated with the irvA-dependent pathway will be identified. The goal of this project is to use the irvA-dependent pathway as a model to examine the connection between stress adaptation and the regulation of important virulence factors of Streptococcus mutans. Since the long-term persistence of S. mutans requires the coordination of stress response mechanisms and virulence factor gene expression, these data may yield new insights into S. mutans cariogenicity.