Rat, a regulator of autolysis in S. aureus

描述（由申请人提供）：S。金黄色葡萄球菌是一种主要的人类病原体;由于出现了抗生素耐药性，因此需要开发新的抗微生物策略。我们已经确定了一个参与自溶的调节系统作为一个新的目标。细菌细胞壁的完整性通常由两个竞争过程维持：细胞壁合成和自溶活性。虽然细胞壁的合成是由PBP介导的，但胞壁蛋白水解酶介导了裂解过程。这两个过程之间的不平衡可能导致细胞溶解。我们最近在S.金黄色;大鼠中的突变导致生长缺陷和胞壁蛋白水解酶活性增加，同时使细胞壁合成相对不受干扰。因此，与亲本菌株相比，大鼠突变体具有增强的去污剂和青霉素诱导的裂解。由于大鼠蛋白与马尔R蛋白家族同源性更高，我们推测大鼠基因产物是S.金黄色。大鼠还抑制另一种称为sarV的基因，该基因是最近描述的SarA蛋白家族的成员。与大鼠相反，sarV中的突变使突变体对裂解更具抗性。我们推测大鼠可能通过抑制sarV来控制S.金黄色。为了了解大鼠和sarV的内在工作机制，并促进新的治疗方法的发展，我们提出了以下五个具体目标：I）表征大鼠和sarV在体外自溶中的相互作用和调节途径; II）评估大鼠和sarV在去污剂和抗生素介导的细胞溶解中的作用; III）确定大鼠和sarV在体外毒力决定因子调节中的作用;（四）通过确定大鼠突变体和高表达SARV的菌株的转录谱和靶向自溶素来评估大鼠和SARV的靶基因。sarV的水平并确定大鼠和SarV结合的基因启动子; IV）在兔心内膜炎模型中评价大鼠和sarV在毒力和对抗生素治疗的应答中的作用。在完成这些研究后，我们希望了解大鼠和sarV在控制自溶的调节剂网络中的作用。我们的长期目标是用抗大鼠或亲SarV策略促进自溶，而不会对毒力产生不利影响。

DESCRIPTION (provided by applicant): S. aureus is a major human pathogen; because of emerging antibiotic resistance, there is a need to develop new antimicrobial strategies. We have identified a regulatory system involved in autolysis as a novel target. The integrity of the cell wall in bacteria is generally maintained by two competing processes: cell wall synthesis and autolytic activity. While synthesis of the cell wall synthesis is mediated by PBP, murein hydrolases mediate the lytic process. An imbalance between these two processes may lead to cell lysis. We recently identified a regulatory locus called rat in S. aureus; a mutation in rat resulted in a growth defect and increased murein hydrolase activity while leaving cell wall synthesis relatively unperturbed. Consequently, the rat mutant had enhanced detergent and penicillin induced lysis as compared with the parental strain. As the Rat protein is more homologous to the MarR protein family, we hypothesize that the rat gene product is a unique regulator of autolytic activity in S. aureus. Rat also represses another gene called sarV, a member of the recently described SarA protein family. Contrary to rat, a mutation in sarV rendered the mutant more resistant to lysis. We speculate that rat may repress sarV to control autolysis in S. aureus. To understand the inner working of rat and sarV and to facilitate the development of a novel therapeutic approach, we propose the following five specific aims: I) characterizing the interaction and regulatory pathways of rat and sarV in autolysis in vitro; II) Evaluating the role of rat and sarV in detergent and antibiotic mediated cell lysis; III) Determining the role of rat and sarV in the regulation of virulence determinants in vitro; IV) Assessing the target genes of rat and sarV by determining the transcriptional profile and target autolysins of the rat mutant and strains expressing a high level of sarV and determining the gene promoters to which Rat and SarV bind; IV) Evaluating the role of rat and sarV in virulence and responses to antibiotic therapy in the rabbit endocarditis model. Upon completion of these studies, we hope to understand the role of rat and sarV within the network of regulators that control autolysis. Our long-term goal is to promote autolysis with an anti-Rat or pro-SarV strategy without developing an untoward impact on virulence.