Elucidating strategies of Staphylococcus aureus nutrient sulfur acquisition during infection

项目总结/摘要 金黄色葡萄球菌是发病和死亡的重要原因，因为其具有显著的能力， 在多个宿主组织中定植。与此同时，S。金黄色葡萄球菌是导致皮肤和软组织 感染、菌血症、骨髓炎和心内膜炎。治疗感染可能非常具有挑战性， 抗生素耐药菌株的流行，这需要开发新的治疗药物， 战略布局在不同的组织中增殖，S。金黄色葡萄球菌通过利用丰富的 宿主环境中的营养库。S.金黄色葡萄球菌营养铁的获取策略已经 研究了几十年;然而，这种病原体为获得同样重要的功能而采用的机制 感染期间的营养硫是未知的。含硫分子的还原和氧化形式， 谷胱甘肽和半胱氨酸在宿主组织中丰富，并支持S.金黄色。是否 这些分子在发病过程中满足硫的需求是未解决的，因为我们不了解 如何S。金黄色葡萄球菌输入并分解代谢这些分子。阐明S.奥瑞斯雇用， 获得宿主来源的谷胱甘肽，我们完成了正向遗传筛选，并确定了不能生长的突变体， 在培养基中补充谷胱甘肽作为唯一的硫源。采用反向遗传方法 以鉴定潜在的半胱氨酸转运蛋白。我们构建了突变体灭活的同源物的推定 氧化半胱氨酸转运蛋白，并显示突变菌株在氧化半胱氨酸利用方面受损， 体外值得注意的是，其中一种进口商在小鼠模型中的肝脏定植方面提供了竞争优势。 全身感染这些初步数据代表了第一个S的鉴定。aureus硫采集系统 支持S.金黄色葡萄球菌靶向丰富的宿主来源的含硫 分子来满足硫的需求。拟议的工作将通过以下方式检验这一假设：（i）建立 支持S.金黄色葡萄球菌的输入和宿主来源的GSH的催化，（ii）鉴定S.金黄色还原 和感染期间氧化半胱氨酸获取策略，和（iii）确定硫源丰度， 在宿主-病原体界面的分布。了解宿主对感染的免疫反应如何影响 组织中的硫源可用性也是本研究的目标。这项工作的完成将揭示 机制S.金黄色葡萄球菌用于在不同组织的定殖期间获得宿主来源的硫源。 这项工作将提供新的治疗策略，以打击抗生素耐药的S。阻碍营养素的金黄色葡萄球菌 硫磺收购我们预测S.金黄色葡萄球菌的硫源获取策略可能在其他 细菌病原体，扩大拟议工作的范围和影响。

PROJECT SUMMARY/ABSTRACT Staphylococcus aureus is a significant cause of morbidity and mortality due to a remarkable capacity to colonize multiple host tissues. Consistent with this, S. aureus is the leading cause of skin and soft tissue infections, bacteremia, osteomyelitis and endocarditis. Treating infections can be exceedingly challenging due to the prevalence of antibiotic resistant isolates, which necessitate the development of new therapeutic strategies. To proliferate within diverse tissues, S. aureus acquires essential nutrients by exploiting abundant nutrient reservoirs present in the host environment. S. aureus nutrient iron acquisition strategies have been studied for decades; however, the mechanisms employed by this pathogen to obtain the equally important nutrient sulfur during infection are not known. Reduced and oxidized forms of the sulfur-containing molecules, glutathione and cysteine, are abundant in host tissues and support in vitro proliferation of S. aureus. Whether these molecules satisfy the sulfur requirement during pathogenesis is unresolved, because we do not understand how S. aureus imports and catabolizes these molecules. To elucidate the mechanisms S. aureus employs to acquire host-derived glutathione, we completed a forward genetic screen and identified mutants that fail to grow in medium supplemented with glutathione as the sole source of sulfur. A reverse genetic approach was pursued to identify potential cysteine transporters. We constructed mutants inactivated for homologues of putative oxidized cysteine transporters and show that the mutated strains are impaired for oxidized cysteine utilization in vitro. Notably, one of the importers provides a competitive advantage in liver colonization in a murine model of systemic infection. These preliminary data represent identification of the first S. aureus sulfur acquisition systems and support the hypothesis that during infection, S. aureus targets abundant host-derived sulfur-containing molecules to satisfy the sulfur requirement. The proposed work will test this hypothesis by (i) establishing the mechanisms that support S. aureus import and catabolism of host-derived GSH, (ii) identifying S. aureus reduced and oxidized cysteine acquisition strategies during infection, and (iii) determining sulfur source abundance and distribution at the host-pathogen interface. Understanding how the host immune response to infection impacts sulfur source availability in tissues is also a goal of this study. The completion of this work will reveal the mechanisms S. aureus employs to acquire host-derived sulfur sources during colonization of distinct tissues. This work will provide novel therapeutic strategies to combat antibiotic resistant S. aureus by impeding nutrient sulfur acquisition. We predict that S. aureus sulfur source acquisition strategies are likely conserved in other bacterial pathogens, broadening the scope and impact of the proposed work.