New mechanisms of sulfur sensing and trafficking in Staphylococcus aureus.

描述（由申请人提供）：革兰氏阳性机会致病菌金黄色葡萄球菌是轻微皮肤感染到更严重的医院和社区获得性疾病的病原体。因此，迫切需要针对新的代谢途径的新的抗生素疗法，而硫代谢代表了一种这样的有效的抗菌和疫苗策略。金黄色葡萄球菌以独特的硫醇代谢为特征，其获得无机硫以制造半胱氨酸（一种必需氨基酸）的能力受到强烈限制。我们在金黄色葡萄球菌菌株Newman中发现了铜敏感转录抑制因子CsoR（铜敏感操纵子抑制因子）的类似物，我们将其标记为CstR，即CsoR样硫转移酶抑制因子。CstR调节一种新的操纵子cst的表达，cst编码一种假定的亚硫酸盐/硫酸盐外排子（TauE），以及两种多结构域蛋白，其中包含典型硫代硫酸盐硫转移酶或罗丹斯结构域（CstA, CstB），其生物学功能尚不清楚。我们的具体目标是：(1)阐明cstr介导的cst操纵子转录抑制和抑制的机制基础；(2)阐明多结构域硫代硫酸盐硫转移酶CstA的结构和机制，我们假设CstA包含三个硫接力模块，共同介导半胱氨酸过硫化物从供体到受体的载体转移。提出了一种新的34S-32SO32-脉冲- 32s - 32so32 -追逐实验；(3)利用“自下而上”的蛋白质组学方法鉴定瞬时携带源自细胞外34S- 32SO3硫代硫酸钠的34S-过硫基团的细胞蛋白；4)开始阐明cstr调控的基因产物CstB（推定的含罗丹斯硫双加氧酶）和SQR（推定的硫化物：醌氧化还原酶）的酶活性。该项目将为人类重要病原体的硫代谢机制和硫代谢物毒性抗性提供新的见解。这些研究将显著扩展其他细菌中基于过硫半胱氨酸的硫穿梭系统的新兴范式，作为一种潜在的新型抗菌干预策略。

DESCRIPTION (provided by applicant): The Gram-positive opportunistic pathogen Staphylococcus aureus is the causative agent of minor skin infections to far more severe hospital and community-acquired diseases. New antibiotic therapies that target novel metabolic pathways are therefore urgently needed and sulfur metabolism represents one such validated antimicrobial and vaccine strategy. Staphylococcus aureus is characterized by a unique thiol metabolism and is strongly restricted in its ability to obtain inorganic sulfur to make cysteine, an essential amino acid. We have discovered a paralog of a copper-sensing transcriptional repressor CsoR (copper-sensitive operon repressor) in S. aureus strain Newman that we denote CstR, for CsoR-like sulfurtransferase repressor. CstR regulates the expression of a novel operon, cst, which encodes a putative sulfite/sulfonate effluxer (TauE) as well as two multidomain proteins that harbor canonical thiosulfate sulfurtransferase or rhodanese domains (CstA, CstB) whose biological functions are unknown. Our specific objectives are to (1) Elucidate the mechanistic basis of CstR-mediated repression and derepression of cst operon transcription; (2) Elucidate the structure and mechanism of the multidomain thiosulfate sulfurtransferase CstA, which we hypothesize harbors three sulfur relay modules that collectively mediate vectorial transfer of cysteine persulfides from donor to acceptor. NMR structural studies and a novel 34S-32SO32- pulse-32S-32SO32- chase experiment are proposed; (3) Identify cellular proteins that transiently carry 34S-persulfide groups originating with extracellular sodium 34S- 32SO3 thiosulfate using a "bottom-up" proteomics approach; and 4) Begin to elucidate the enzymatic activities of CstR-regulated gene products CstB, a putative rhodanese-containing sulfur dioxygenase and SQR, a putative sulfide:quinone oxidoreductase. This project will provide new insights into the mechanisms of sulfur metabolism and resistance to sulfur metabolite toxicity in an important human pathogen. These studies will significantly extend the emerging paradigm of a cysteine persulfide-based sulfur shuttling system in other bacteria to a new metabolic process as a potential novel antimicrobial intervention strategy.