Osmotic stress regulation and the role of cyclic di-adenosine monophosphate (c-di-AMP) in Staphylococcus aureus

这项提案中描述的工作旨在深入了解金黄色葡萄球菌的渗透胁迫是如何调节的，以及c-双-AMP在这一过程中扮演了什么角色。金黄色葡萄球菌是一种机会性病原体，可引起多种疾病，如菌血症、中毒性休克综合征、心内膜炎和败血症。它也是一种常见的食源性病原体，这在一定程度上是由其抵御外部高浓度盐的能力所致，这是一种经常用于食物保存的技术。到目前为止，这种渗透胁迫抗性背后的机制(S)还知之甚少，阻止这一过程的能力可能有助于预防金黄色葡萄球菌通过食物传播的感染。一般来说，金黄色葡萄球菌对渗透性上激波的反应是通过引入钾离子和称为相容溶质的小有机分子来抵消水的外流。目前的数据表明，最近发现的第二信使环二腺苷一磷酸(c-di-AMP)参与了这一过程，因为金黄色葡萄球菌中的几个c-di-AMP受体蛋白调节钾运输系统的表达或活性。在一个尚未发表的其他c-di-AMP结合蛋白的筛选中，发现了一种新的c-di-AMP受体蛋白，可能与渗透调节物质的摄取有关。因此，本项目旨在深入研究这种渗透压转运蛋白的功能特征，阐明c-diAMP对其功能的调节作用，并确定其在金黄色葡萄球菌中的生理作用。为了更好地了解金黄色葡萄球菌对盐胁迫的一般反应，将使用基于TN-SEQ的方法在全基因组水平上确定在盐胁迫条件下金黄色葡萄球菌哪些基因是必需的，以及c-di-AMP是如何参与这一过程的。有希望的候选基因随后将得到进一步的验证和表征。综上所述，这些实验将有助于我们理解金黄色葡萄球菌如何适应和生存在高盐环境中，以及c-di-AMP在这一背景下所扮演的角色。

The work described in this proposal aims to provide insight into how osmotic stress is regulated in Staphylococcus aureus and what role c-di-AMP plays in this process. S. aureus is an opportunistic pathogen that causes a variety of diseases such as bacteremia, toxic shock syndrome, endocarditis and sepsis. It is also a common food borne pathogen, which is in part mediated by its ability to withstand high external concentrations of salt, a technique often used for the preservation of food. So far, the mechanism(s) behind this osmotic stress resistance is only poorly understood and the ability to impede this process could help to prevent S. aureus food borne infections. In general, S. aureus reacts to osmotic upshock with the import of potassium ions and small organic molecules called compatible solutes to counteract the efflux of water. Current data indicate that the recently discovered second messenger cyclic di-adenosine monophosphate (c-di-AMP) is involved in this process, as several c-di-AMP receptor proteins in S. aureus regulate the expression or activity of potassium transport systems. In an as yet unpublished screen for additional c-di-AMP binding proteins, a novel c-di-AMP receptor protein, likely involved in the uptake of osmolytes, was discovered. This project therefore aims to functionally characterize this osmolyte transporter in depth, elucidate the regulatory role of c-di-AMP on its function and determine its physiological role in S. aureus. In order to gain a greater understanding of how S. aureus reacts to salt stress in general, a TN-seq based approach will be used to determine on a genome wide level which genes are essential in S. aureus under salt stress conditions and how c-di-AMP is involved in this process. Promising candidate genes will then be further validated and characterized. Together, these experiments will contribute to our understanding of how S. aureus adapts and survives in high salt environments and what role c-di-AMP plays in this context.