Rat, a regulator of autolysis in S. aureus

大鼠，金黄色葡萄球菌自溶调节因子

• 批准号: 6875935
• 负责人: Ambrose Lin Yau Cheung
• 金额: $ 39.91万
• 依托单位: DARTMOUTH COLLEGE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6875935
• 关键词: Staphylococcus aureus; bacterial endocarditis; bacterial genetics; cell autolysis; cell wall; enzyme activity; gene expression; genetic regulatory element; hydrolase; laboratory mouse; laboratory rabbit; virulence

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.

描述（由申请人提供）：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，需要制定新的抗菌策略。我们已经确定了参与自溶的调控系统作为新目标。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，但胞壁质水解酶介导裂解过程。这两个过程之间的不平衡可能导致细胞裂解。我们最近在金黄色葡萄球菌中发现了一个称为大鼠的调节位点；大鼠体内的突变导致生长缺陷并增加了胞壁质水解酶活性，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 Rat 蛋白与 MarR 蛋白家族更加同源，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。大鼠还抑制另一种名为 sarV 的基因，该基因是最近描述的 SarA 蛋白家族的成员。与大鼠相反，sarV 中的突变使突变体对裂解具有更强的抵抗力。我们推测大鼠可能抑制 sarV 以控制金黄色葡萄球菌的自溶。为了了解大鼠和 sarV 的内部工作原理并促进新型治疗方法的开发，我们提出以下五个具体目标： 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在去垢剂和抗生素介导的细胞裂解中的作用； III)确定大鼠和sarV在体外毒力决定子调节中的作用； IV)通过确定表达高水平sarV的大鼠突变体和菌株的转录谱和靶标自溶素以及确定Rat和SarV结合的基因启动子来评估大鼠和sarV的靶基因； IV) 评估大鼠和 sarV 在兔心内膜炎模型中的毒力和抗生素治疗反应中的作用。完成这些研究后，我们希望了解大鼠和 sarV 在控制自溶的调节网络中的作用。我们的长期目标是通过抗大鼠或亲 SarV 策略促进自溶，而不会对毒力产生不良影响。