Interaction and interdependency of GlmM and DacA - two essential enzymes required for methicillin resistance in Staphylococcus aureus

金黄色葡萄球菌常见于健康人的皮肤、鼻腔或其他粘膜表面，不会引起任何症状或伤害。然而，金黄色葡萄球菌也可以引起各种各样的感染，从小的皮肤感染到危及生命的侵袭性疾病。令人震惊的是，许多金黄色葡萄球菌菌株已经获得了对多种抗菌素的耐药性，因此金黄色葡萄球菌仍然是世界范围内耐抗生素卫生保健相关感染的主要原因之一。由此造成的治疗这些感染的困难是一个主要的公共卫生问题。因此，研究细菌生长所需的生物合成途径和酶，最终开发出新的抗菌素是很有意义的。本研究的目的是表征两种葡萄球菌酶GlmM和DacA的相互作用和相互依赖性。这两种酶对金黄色葡萄球菌的生长都非常重要。乍一看，它们之间没有明显的联系，因为GlmM是产生基本细胞壁前体所必需的，而DacA负责产生最近发现的信号核苷酸c-di-AMP。然而，最近的研究表明，这两种酶之间存在直接的蛋白质/蛋白质接触，这表明它们调节的途径在某种程度上是相互关联的。因此，DacA和GlmM在协调细胞壁聚合物肽聚糖的合成过程中具有潜在的核心作用，这些合成途径由c-二磷酸腺苷调节。该项目的目的是提供DacA/GlmM复合物的图像，以准确显示这两种蛋白质是如何相互作用的，找出一种酶的活性如何影响另一种酶的活性，以及这种相互作用如何影响细胞的生长和甲氧西林耐药性。总之，这项工作将对两种重要的细菌酶的相互依赖性提供有价值的信息，这两种重要的细菌酶连接了革兰氏阳性细菌金黄色葡萄球菌的两个基本细胞过程。由于金黄色葡萄球菌与人类感染的直接联系，这项关于基本细胞途径的工作的成果可能为未来开发干扰金黄色葡萄球菌和其他一些潜在革兰氏阳性病原体生长的新治疗方法提供机会。

Staphylococcus aureus is frequently found on the skin, nares or other mucosal surfaces of healthy individuals without causing any symptoms or harm. However, S. aureus can also cause a wide variety of infections ranging from small skin infections to life-threatening invasive diseases. Alarmingly, many S. aureus strains have acquired resistance to multiple antimicrobials and as a result S. aureus is still one of the leading causes of antibiotic-resistant healthcare-associated infections worldwide. The resulting difficulty in treating these infections is a major public health concern. Therefore, it is of interest to study biosynthesis pathways and enzymes that are required for bacterial growth to ultimately develop new antimicrobials. The purpose of this study is to characterize the interaction and interdependency of the two staphylococcal enzymes GlmM and DacA. Both enzymes are extremely important for the growth of S. aureus. At the first glance there is no apparent connection between them as GlmM is required for the production of an essential cell wall precursor and DacA is responsible to the production of a recently discovered signalling nucleotide c-di-AMP. However, recent work has indicated that there is a direct protein/protein contact between these two enzymes, suggesting that the pathways that they regulate are somehow interconnected. DacA and GlmM are therefore potentially central players in coordinating the synthesis of the cell wall polymer peptidoglycan with pathways that are regulated by c-di-AMP. The aims of this project are to provide an image of the DacA/GlmM complex in order to show exactly how these two proteins interact, find out how the activity of one enzyme influences the activity of the other and how this interaction affects the growth and methicillin resistance of the cell. In summary, the work will yield valuable information on the interdependency of two important bacterial enzymes, which interconnect two essential cellular processes in the Gram-positive bacterial pathogen S. aureus. Due to the direct link of S. aureus to human infection, the output of this work on essential cellular pathways can potentially offer future opportunities for the development of novel therapeutic approaches interfering with the growth of S. aureus and potentially a number of other Gram-positive pathogens.