Citric acid cycle regulation of exopolysaccharide synthesis in staphylococci

描述（由申请方提供）：金黄色葡萄球菌和表皮葡萄球菌是导致多种人类和动物疾病的条件致病菌。重要的是，S。金黄色葡萄球菌和表皮病是医院相关感染的两个主要原因，这显著增加了发病率和治疗费用。胞外多糖是葡萄球菌感染的重要介质;具体而言，多糖细胞间粘附素（PIA）增强生物膜形成和免疫逃避，而荚膜促进免疫逃避、定殖和持久性。当三羧酸（TCA）循环活性受到抑制时，葡萄球菌合成PIA。与此相反，S.金黄色葡萄球菌荚膜多糖需要TCA循环活性。有趣的是，PIA和胶囊衍生自相同的氨基糖（即，UDP-N-乙酰葡糖胺。这两种胞外多糖的合成受营养素、氧和铁的可用性调节。类似地，TCA循环活性受营养素、氧和铁的可用性以及某些应激诱导刺激（如热、乙醇和抗生素）的调节。TCA循环活性和胞外多糖合成的联系以及TCA循环对环境失活的敏感性使我们假设葡萄球菌感知外部环境变化的一种机制是通过TCA循环活性的改变。TCA循环活性的这些变化改变了细菌代谢物组，增加或降低了由调节蛋白“感测”的代谢物和辅因子的细胞内浓度，这增加或降低了胞外多糖的生物合成。该提案的目的是鉴定控制胞外多糖合成的TCA循环代谢物，并确定哪些调节蛋白响应于这些TCA循环代谢物来调节胞外多糖合成。为了实现这些目标，我们将使用系统生物学，生物化学，生物信息学和遗传学相结合的综合方法。拟议研究的基本原理是填补我们对环境条件如何影响细菌代谢状态以及代谢状态如何影响葡萄球菌胞外多糖生物合成的理解中的差距。理解这一点将有助于我们的长期目标，即设计针对葡萄球菌代谢和代谢反应调节剂的治疗策略，以促进抗生素和宿主免疫系统的细菌杀灭。

DESCRIPTION (provided by applicant): Staphylococcus aureus and Staphylococcus epidermidis are opportunistic bacterial pathogens responsible for a wide array of human and animal diseases. Importantly, S. aureus and S. epidermidis are the two leading causes of hospital-associated infections, which significantly increase morbidity and treatment costs. Exopolysaccharides are important mediators of staphylococcal infections; specifically, polysaccharide intercellular adhesin (PIA) enhances biofilm formation and immune evasion, while capsule facilitates immune evasion, colonization, and persistence. Staphylococcal PIA is synthesized when tricarboxylic acid (TCA) cycle activity is repressed. In contrast, synthesis of the S. aureus capsular polysaccharide requires TCA cycle activity. Interestingly, PIA and capsule are derived from the same amino sugar (i.e., UDP-N-acetyl-glucosamine. Synthesis of both exopolysaccharides is modulated by the availability of nutrients, oxygen, and iron. Similarly, TCA cycle activity is regulated by the availability of nutrients, oxygen, and iron and by certain stress-inducing stimuli such as heat, ethanol, and antibiotics. The linkage of TCA cycle activity and exopolysaccharide synthesis and the susceptibility of the TCA cycle to environmental inactivation lead us to hypothesize that one mechanism by which staphylococci perceive external environmental change is through alterations in TCA cycle activity. These changes in TCA cycle activity alter the bacterial metabolome increasing or decreasing the intracellular concentrations of metabolites and co- factors that are "sensed" by regulatory proteins, which increase or decrease exopolysaccharide biosynthesis. The aims of this proposal are to identify the TCA cycle metabolites that control exopolysaccharide synthesis and determine which regulatory proteins are responding to these TCA cycle metabolites to regulate exopolysaccharide synthesis. To achieve these aims, we will use an integrated approach combining systems biology, biochemistry, bioinformatics, and genetics. The rationale for the proposed research is to fill the gap in our understanding of how environmental conditions affect the bacterial metabolic status and, in turn, how the metabolic status affects staphylococcal exopolysaccharide biosynthesis. Understanding this will aid in our long-term goal, which is to design therapeutic strategies targeting staphylococcal metabolism and metabolic responsive regulators that will facilitate bacterial killing by antibiotics and the host immune system.