Rat, a regulator of autolysis in S. aureus

描述(申请人提供)：金黄色葡萄球菌是一种主要的人类病原体；由于新出现的抗生素耐药性，有必要开发新的抗菌策略。我们已经确定参与自溶的调节系统是一个新的靶点。细菌细胞壁的完整性通常由两个相互竞争的过程维持：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murein水解酶介导了裂解过程。这两个过程之间的不平衡可能会导致细胞溶解。我们最近在金黄色葡萄球菌中发现了一个名为rat的调节位；大鼠的一个突变导致了生长缺陷和毛尿素水解酶活性的增加，而细胞壁的合成相对不受干扰。因此，与亲本菌株相比，突变体提高了洗涤剂和青霉素诱导的裂解能力。由于大鼠蛋白与MARR蛋白家族有更多的同源性，我们假设大鼠基因产物是金黄色葡萄球菌自溶活性的独特调节因子。RAT还抑制另一种名为Sarv的基因，该基因是最近描述的Sara蛋白家族的成员。与老鼠相反，SARV的突变使突变体对裂解更具抵抗力。我们推测，大鼠可能通过抑制SARV来控制金黄色葡萄球菌的自溶。为了了解大鼠和SARV的内部机制，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：1)研究大鼠和SAV在体外自溶中的相互作用和调控途径；2)评价大鼠和SAV在洗涤剂和抗生素介导的细胞裂解中的作用；3)确定大鼠和SAV在体外调节毒力决定因素中的作用；4)通过测定高表达SAV的大鼠突变体和菌株的转录谱和靶自溶蛋白，以及确定大鼠和SAV结合的基因启动子，来评估大鼠和SAV的靶基因；Iv)在兔心内膜炎模型中，评估大鼠和SARV在毒力和抗生素治疗反应中的作用。在完成这些研究后，我们希望了解RAT和SARV在控制自溶的调节网络中的作用。我们的长期目标是在不对毒力产生不利影响的情况下，通过抗大鼠或支持SARV的策略促进自溶。

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.