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

描述（由申请人提供）：拟议的研究旨在研究变形链球菌通过irvA依赖性途径进行基因调控的遗传和生化机制。该项目的目标将通过以下三个目标来实现：1) 分析 irvA 诱导机制 2) 识别 IrvA 调节子 3) 表征构成 irvA 依赖性途径的遗传调节因子。 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，以确定其内源自切割能力如何调节其控制irvA表达的能力。 2) 为了鉴定 IrvA 调节子，我们将采用染色质免疫沉淀和微阵列（ChIP 芯片）。使用专门设计的 Affymetrix Genechips(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的基因转录调节因子的作用。 3）为了表征irvA依赖性途径的遗传调节因子，我们将首先鉴定能够诱导irvA的基因。然后，遗传分析将检查 irvA 作为这些菌株中应激和毒力相关表型的介质的作用。最后，将鉴定与irvA依赖性途径共同调节的基因。该项目的目标是使用irvA依赖性途径作为模型来研究应激适应与变形链球菌重要毒力因子调节之间的联系。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，这些数据可能会对变形链球菌的致龋性产生新的见解。 公众健康相关性：龋齿是最常见的人类细菌性疾病，在很大程度上与变形链球菌的过度生长相关。由于这种生物体引起疾病的能力需要仔细协调其应激反应和毒力，因此这些研究可能会产生新的治疗策略来控制变形链球菌的发病机制。

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. PUBLIC HEALTH RELEVANCE: Dental caries is the most common human bacterial disease and is largely correlated with the overgrowth of Streptococcus mutans. Since this organism's ability to cause disease requires careful coordination of its stress response and virulence, these studies may yield novel treatment strategies to control the pathogenesis of S. mutans.