柠檬醛调控耐甲氧西林金黄色葡萄球菌lrgAB基因表达的机制研究

耐甲氧西林金黄色葡萄球菌（MRSA）因常表现为多重耐药，可供临床使用的药物有限，寻找安全有效的新型抗菌活性物质迫在眉睫。柠檬醛是一种安全无毒的天然活性物质，具有抗菌、抗炎等活性。申请人研究发现，柠檬醛具有显著的体外和体内抗MRSA感染疗效；并能显著增强多种抗生素的抗菌活性，可减少抗生素用量。抗菌作用机制研究表明柠檬醛可显著下调lrgAB基因的表达，增强自溶酶活性，降解MRSA细胞；生信分析显示lrgAB基因表达受lytSR双组份系统调控，但柠檬醛如何调控lrgAB基因的表达尚不清楚。因此，本研究将解决以下科学问题：1.通过报告基因系统、凝胶阻滞等实验解析柠檬醛对lrgAB基因启动子的调控作用。2.采用流式细胞术、基因敲除与回补等技术阐明柠檬醛如何通过lytSR双组份系统调控lrgAB的信号通路。研究成果将对柠檬醛调控基因表达的分子机制研究奠定理论基础，为柠檬醛有效开发利用提供科学支撑。

Due to the multi-drug resistance of Methicillin resistant Staphylococcus aureus (MRSA) the available drugs for clinical use are limited. It is urgent to find new safe and effective antibacterial active substances. Citral is a safe and nontoxic natural active substance with antibacterial and anti-inflammatory activities. The applicant found that citral has significant in vitro and in vivo anti-MRSA effect and can significantly enhance the antibacterial activity of a variety of antibiotics, reduce the dosage of antibiotics. The study of antibacterial mechanism showed that citral could significantly down regulate the expression of lrgAB gene, enhance the activity of autolyase, and degrade MRSA cells; Bioinformatics analysis showed that the expression of lrgAB gene was regulated by two component system lytSR, but how citral regulated the expression of lrgAB gene was not clear. Therefore, this study will solve the following scientific problems: 1. through the reporter gene system and electrophoretic mobility shift assay, we can analyze the regulatory effect of citral on the promoter of lrgAB gene. 2. Flow cytometry, gene knockout and complementation were used to elucidate how citral regulates the signal pathway of lrgAB by regulating lytSR. The research results will lay a theoretical foundation for the molecular mechanism of citral regulating gene expression, and provide scientific support for the effective development and utilization of citral.