Significance of four methionine sulfoxide reductases in Staphylococcus aureus

描述（由申请方提供）：PI实验室的长期目标是了解金黄色葡萄球菌发病机制的遗传基础，并找到克服其表达抗生素耐药性的方法。本研究的目的是确定蛋氨酸亚砜还原酶（Msr）酶在这种生物体中的确切生理作用。蛋白质结合的甲硫氨酸残基的氧化导致生物活性的丧失。Msr酶减少氧化应激下产生的甲硫氨酸亚砜（MetO）并恢复蛋白质功能。S.用细胞壁活性抗生素处理的金黄色葡萄球菌细胞产生升高量的Msr酶。S.金黄色葡萄球菌具有编码参与MetO的S-差向异构体还原的蛋白质的三个基因（msrA 1、msrA 2和msrA 3）和编码参与MetO的R-差向异构体还原的蛋白质的基因msrB。为什么是S。金黄色葡萄球菌具有多种功能明显重叠或冗余的蛋白质，它们在生理学和毒力中的作用尚不清楚。据推测，编码这些Msr蛋白的基因在不同的环境条件下差异表达，其产物保护S。金黄色葡萄球菌。为了验证这一假设，已经构建了各种报告基因和msr突变株。记者S。金黄色葡萄球菌菌株将用于在适当的生长条件下确定负责产生四种Msr蛋白的基因的表达模式。为该研究构建的三种独特msr突变体包括msrB突变体（缺乏还原R-MetO的能力）;三重msr突变体（msrA 1、msrA 2、msrA 3;缺乏还原S-MetO的能力）;和四重msr突变体（msrA 1、msrA 2、msrA 3、msrB;缺乏还原R-或S-MetO的能力）。这些突变体将用于确定Msr蛋白在葡萄球菌生理学和毒力中的确切作用，通过进行适当的体外和体内实验。这项研究将为杜鲁门州立大学的本科生和ATSU的研究生提供广泛的研究培训。本研究的完成将有助于更好地了解四种Msr蛋白在S.金黄色葡萄球菌和开辟途径，以控制由这种病原体引起的感染。 公共卫生相关性：金黄色葡萄球菌是一种重要的人类病原体。抗生素处理的S.金黄色葡萄球菌细胞产生升高量的甲硫氨酸亚砜还原酶（Msr）蛋白。确定这四种Msr蛋白的确切生理作用将有助于理解一般的胁迫耐受性和特别是S.金黄色葡萄球菌，并建议新的治疗策略，控制葡萄球菌感染。

DESCRIPTION (provided by applicant): The long-term goal of the PI's laboratory is to develop an understanding of the genetic basis of Staphylococcus aureus pathogenesis and find ways to overcome its ability to express resistance to antibiotics. The purpose of this study is to determine precise physiological roles of methionine sulfoxide reductase (Msr) enzymes in this organism. Oxidation of protein bound methionine residues leads to loss of biological activity. Msr enzymes reduce methionine sulfoxide (MetO) generated under oxidative stress and restore protein function. S. aureus cells treated with cell wall-active antibiotics produce elevated amounts of Msr enzymes. S. aureus possesses three genes that encode proteins involved in the reduction of the S-epimer of MetO (msrA1, msrA2, and msrA3) and a gene, msrB, that encodes a protein involved in the reduction of the R-epimer of MetO. Why S. aureus possesses multiple proteins with apparently overlapping or redundant functions, and their roles in physiology and virulence are not clear. It is hypothesized that the genes encoding these Msr proteins are expressed differentially under different environmental conditions and that their products protect S. aureus from stress conditions. To test this hypothesis, various reporter and msr mutant strains have been constructed. The reporter S. aureus strains will be used to determine, under appropriate growth conditions, the expression patterns of the genes that are responsible for producing the four Msr proteins. The three unique msr mutants constructed for this study include an msrB mutant (lacks ability to reduce R-MetO); a triple msr mutant (msrA1, msrA2, msrA3; lacks ability to reduce S-MetO); and a quadruple msr mutant (msrA1, msrA2, msrA3, msrB; lacks ability to reduce either R- or S-MetO). These mutants will be used to determine the precise roles of Msr proteins in staphylococcal physiology and virulence by conducting appropriate in vitro and in vivo experiments. This study will provide extensive research training for Truman State University undergraduate and ATSU graduate students. Completion of the study will provide a better understanding of the significance of four Msr proteins in S. aureus and open avenues to control infections caused by this pathogen. PUBLIC HEALTH RELEVANCE: Staphylococcus aureus is a significant human pathogen. Antibiotic treated S. aureus cells produce elevated amounts of methionine sulfoxide reductase (Msr) proteins. Determination of the precise physiological roles of the four Msr proteins will help understand stress tolerance in general and antibiotic resistance in particular in S. aureus, and should suggest new therapeutic strategies for the control of staphylococcal infections.