Elucidation of the Molecular Mechanism of Staphylococcus aureus response to cell wall damage

拟议的研究计划旨在了解金黄色葡萄球菌对细胞壁损伤的反应。细菌细胞壁是细菌的第一道防线，因此其完整性处于持续的压力下。革兰氏阳性细菌的细胞壁由糖肽聚合物（称为肽聚糖）和共价连接至肽聚糖的聚阴离子聚合物（称为壁磷壁酸）组成。两种聚合物的完整性对于细菌细胞生长和分裂是不可或缺的，并且在病原菌的情况下，它们对于定殖和宿主感染是不可或缺的。基于基因组的细胞壁抑制剂活性分析研究表明，一般细菌和S。金黄色葡萄球菌特别具有复杂的信号传导机制，以感知和响应细胞壁损伤。许多信号转导和代谢途径似乎与细胞壁损伤的反应有关，与损伤发生在途径中的位置无关。关于信号转导通路如何起作用以及如何共同应对细胞壁损伤的细节还缺乏。* 拟议的研究计划侧重于双组分系统VraSR和GraSR以及S.金黄色。VraSR被认为是细胞壁完整性的哨兵。我的小组是第一个提供VraSR信号转导动力学并揭示VraR调控机制的小组（Belcheva et al. J. Biol. Chem，2008; Belcheva et al. Biochemistry 2009）。最近的研究表明，S。金黄色葡萄球菌可能涉及另一种蛋白质通过VraSR，VraT调节信号传导。GraSR参与调节壁磷壁酸，我们目前的研究表明，GraS利用与VraSR不同的机制进行信号传导（Muzamal et al. F1000 Prime，2014）。Stk 1/Stp参与细胞壁合成的调节，并且我们的小组显示其与GraSR相互作用（Fridman et al. Biochemistry，2013）。此外，我们最近发现Stk 1/Stp磷酸化一种参与细胞壁合成的蛋白质。* 该提案的目标是双重的：了解上述系统的信号机制及其在S.金黄色葡萄球菌对细胞壁损伤的反应。我的实验室拥有蛋白质化学、分子生物学和微生物学方面的专业知识，以实现上述目标。该研究项目是对S.金黄色。预计将获得的知识在这个程序将是非常感兴趣的研究社区参与微生物应激反应，细胞壁生物合成和基因调控的研究。

The proposed research program aims understanding the Staphylococcus aureus response to cell wall damage. Bacterial cell wall is the first line of defense in bacteria and as such its integrity is under constant stress. Cell wall in Gram-positive bacteria consists of a glycopeptide polymer, referred to as peptidoglycan, and a polyanionic polymer covalently attached to peptidoglycan, referred to as wall teichoic acid. Integrity of both polymers is indispensable to bacterial cell growth and division, and in the case of pathogenic bacteria they are indispensable to colonization and host infection.***Genome-based studies on profiling the activity of cell wall inhibitors have revealed that bacteria in general and S. aureus is particular have complex signaling mechanisms in place to sense and respond to cell wall damage. A number of signal transduction and metabolic pathways appear to be involved with the response to cell wall damage, independent of where in the pathway the damage occurs. The details of how the signal-transduction pathways function and work together to respond to cell wall damage are lacking. ***The proposed research program focuses on the molecular mechanisms of signal-transduction by two-component systems VraSR and GraSR and the eukaryotic- like serine/threonine kinase/phosphatase Stk1/Stp of S. aureus. VraSR is considered the sentinel of cell wall integrity. My group was the first to provide the kinetics of signal-transduction by VraSR and revealed the regulatory mechanism of VraR (Belcheva et al. J. Biol. Chem, 2008; Belcheva et al.  Biochemistry 2009). Recent reports show that S. aureus may involve another protein in tuning signaling by VraSR, VraT. GraSR is involved in modulation of wall teichoic acid, and our current research indicates that GraS utilizes a different mechanism than VraSR for signaling (Muzamal et al. F1000 Prime, 2014). Stk1/Stp is involved in regulation of cell wall synthesis and was shown by our group to interact with GraSR (Fridman et al. Biochemistry, 2013). Moreover, we recently discovered that Stk1/Stp phosphorylates a protein involved with cell wall synthesis. ***The objectives of the proposal are two-fold: understand signaling mechanisms of the above systems and their interplay in S. aureus response to cell wall damage. My laboratory has expertise in protein chemistry, molecular biology and microbiology to achieve the above objectives. The proposed research program constitutes a basic research on stress response mechanisms, gene functions and regulation in S. aureus. The knowledge anticipated to be gained in this program will be of great interest to research communities involved in studies of microbial stress responses, cell wall biosynthesis and gene regulation.***********