Regulation of Virulence by luxS in Staphylococcus aureus

描述(申请人提供)：金黄色葡萄球菌是一种机会致病菌，由于能够产生多种毒力因子而导致多种疾病。其中一些因素受到群体感应系统AGR的调节。最近，一种新的群体感应系统(LUXS)被发现。LUXS系统广泛存在于各种细菌中，它调节几种病原体的毒力因子。金黄色葡萄球菌拥有一个在所有菌株中都保守的LuxS同源基因。LUXS在金黄色葡萄球菌毒力调节中的作用尚未得到研究。我们的目标是填补这一空白，作为开发治疗葡萄球菌感染的治疗方案的先决条件。在拟议的研究中，假设LUXS系统调节毒力因子的表达，并与两个主要的全球调节因子SarA和agr进行沟通。该项目的具体目标是：1)评估LUX S在调节葡萄球菌毒力因子中的作用。在金黄色葡萄球菌中，LuxS基因通过插入失活而发生突变。利用实时定量聚合酶链式反应(RT-qPCR)和Western blotting，分析了几种毒力因子在LuxS突变体中的表达，并与野生型进行了比较。2)描述LUXS系统和AGR系统之间可能存在的串扰。与LuxS突变相关的agr的转录变化将被定义。用RT-qPCR方法检测AGR效应分子(RNAIII)的表达。也将在agr突变体中评估LuxS的转录，以确定agr对LuxS表达的任何影响。双突变株(agr-LuxS)的表型也将被研究。3)定义了LUXS和SARA之间的相互作用。为了确定全局调控因子SarA对LuxS的影响，我们将用RT qPCR方法检测一个SarA突变体中LuxS的表达。将在LuxS突变体中检测SarA及其同源物的表达，以确定LuxS对这些调控因子的影响。还将对双突变体(Sara-LuxS)的表型进行研究。

DESCRIPTION (provided by applicant): Staphylococcus aureus is an opportunistic pathogen that causes a wide range of diseases due to ability to produce a wide variety of virulence factors. Some of these factors are regulated by agr, a quorum sensing system. Recently, a novel quorum sensing system (luxS) has been discovered. The luxS system is found in a wide variety of bacteria and it regulates virulence factors in several pathogens. S. aureus possesses a luxS homolog that is conserved in all strains. The role of luxS in the regulation of virulence in S. aureus has not yet been investigated. Our goal is to fill this gap as a prerequisite to developing therapeutic protocols for treatment of staphylococcal infections. In the proposed research, the hypothesis is that luxS system regulates the expression of virulence factors and that it communicates with the 2 main global regulators sarA and agr. The specific aims of the proposed project are: 1) Assess the role of luxS in the regulation of staphylococcal virulence factors. The luxS gene was mutated in S. aureus by insertional inactivation. Using real-time quantitative PCR (RT qPCR) and Western blotting, expression of several virulence factors will be analyzed in the luxS mutant and compared to wild type. 2) Characterize possible crosstalk between the luxS system and the agr system. Transcriptional changes in agr associated with mutation of luxS will be defined. Expression of the agr effector molecule (RNAIII) will be measured by RT qPCR. The transcription of the luxS will also be evaluated in an agr mutant to define any effect of agr on luxS expression. The phenotype of the double mutant (agr-luxS) will also be studied. 3) Define the interaction between luxS and sarA. To define the effect of the global regulator sarA on luxS, expression of luxS will be examined in a sarA mutant by RT qPCR. The expression sarA and its homologs will be examined in the luxS mutant to define the effect of luxS on these regulators. The phenotype of the double mutant (sarA-luxS) will also be studied.