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

提出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，因此其完整性受到持续的压力。革兰氏阳性菌细胞壁由糖肽聚合物（称为肽聚糖）和聚阴离子共价附着于肽聚糖的聚合物（称为壁磷壁酸）组成。这两种聚合物的完整性对于细菌细胞的生长和分裂是必不可少的，在致病菌的情况下，它们对于定植和宿主感染是必不可少的。基于基因组的细胞壁抑制剂活性分析研究表明，一般细菌，特别是金黄色葡萄球菌，具有复杂的信号机制来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，而与损伤发生的途径无关。信号转导途径如何发挥作用并共同作用以应对细胞壁损伤的细节尚不清楚。***拟重点研究金黄色葡萄球菌双组分系统VraSR和GraSR以及真核样丝氨酸/苏氨酸激酶/磷酸酶Stk1/Stp信号转导的分子机制。VraSR被认为是细胞壁完整性的哨兵。我的小组首次提供了VraSR信号转导的动力学，并揭示了VraR的调控机制（Belcheva等）。生物。化学,2008;Belcheva等人。生物化学2009)。最近的报道表明，金黄色葡萄球菌可能涉及VraSR信号调节的另一种蛋白VraT。GraSR参与壁壁壁酸的调节，我们目前的研究表明，GraS利用不同于VraSR的信号传导机制（Muzamal等）。F1000 Prime, 2014)。Stk1/Stp参与细胞壁合成的调控，并被我们的团队证明与GraSR相互作用（friedman等）。生物化学,2013)。此外，我们最近发现Stk1/Stp磷酸化了一种参与细胞壁合成的蛋白质。***该提案的目的有两个：了解上述系统的信号机制及其在金黄色葡萄球菌对细胞壁损伤的反应中的相互作用。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来实现上述目标。本研究项目是对金黄色葡萄球菌应激反应机制、基因功能及调控的基础性研究。预期在本课程中获得的知识将对参与微生物应激反应，细胞壁生物合成和基因调控研究的研究团体产生极大的兴趣。***********

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.***********