Characterisation of the Ess protein secretion system of Staphylococcus aureus, a key virulence factor.

几乎所有的细菌都是通过分泌毒素进入宿主体内而引起疾病的。这些毒素中的许多是蛋白质分子，细菌在细胞膜中有专门的机器，允许这些毒素受控地传递到外部。我们正在研究其中一种机器-最近发现的Ess系统-寻求了解微生物学的一个核心方面，即蛋白质分泌机器如何工作。该系统已被证明是金黄色葡萄球菌的毒力所必需的。金黄色葡萄球菌是一种革兰氏阳性细菌，可引起人类的多种疾病，从轻微的皮肤感染，如丘疹和脓疱，中毒性休克综合征，到败血症和肺炎。它是最广为人知的医院获得性感染的主要原因，也是手术后伤口感染的常见原因。这种情况由于某些S.金黄色葡萄球菌对许多抗生素具有抗性（例如耐甲氧西林金黄色葡萄球菌; MRSA），使其成为严重且难以治疗的问题。在分子水平上对S.我们的初步工作和其他人的结果表明，Ess转运系统驱动金黄色葡萄球菌分泌至少五种不同的蛋白质。金黄色葡萄球菌，并且已知当该系统失活时，S.金黄色葡萄球菌显示其引起感染的能力显著降低。我们寻求这种独特的细菌分泌机器的结构和功能的知识，并确定其中一种分泌蛋白质的功能。为了分泌蛋白质，机器需要通电。很有可能是BKC蛋白负责为这一过程提供能量，通过分解细胞中一种富含能量的化合物ATP。我们想了解机器如何工作的分子基础。我们通过纯化和结晶大部分的CCLC蛋白质，在这方面取得了重大进展。我们现在希望利用单晶X-射线衍射方法来推导出一个准确的分子结构的C4 H1 C。我们希望在此基础上，通过了解Ess机器中的Ess C如何结合和水解ATP，以及它与哪些其他蛋白质相互作用。我们希望确认我们的初步结果，以确定哪些蛋白质由该机器分泌。我们想确定其中一种蛋白质的分子结构，以了解它们是如何工作的。最后，我们想了解这些蛋白质是如何被机器分泌的，特别是看看它们在输出过程中是否与CD 3C相互作用。了解蛋白质组分的结构以及它们如何相互作用是很重要的，因为从长远来看，为设计或发现化合物的研究奠定基础，这些化合物将阻止这些蛋白质相互作用或阻止蛋白质相互作用。从被用来分泌出的蛋白质，建立和延长感染的动力。关于分泌的蛋白质和在细菌表面发现的结构的信息也可以为疫苗设计提供机会。

Almost all bacteria cause disease by producing toxins that they secrete into the host. Many of these toxins are protein molecules, and the bacterium has specialised machines in the cell membrane that allows the controlled passage of these toxins to the outside. We are working on one of these machines - the recently discovered Ess system - seeking to understand a central aspect of microbiology, namely how protein secretion machines work. This system has been shown to be essential for the virulence of Staphylococcus aureus.S. aureus is a commensal Gram positive bacterium responsible for a number of illnesses in humans ranging from minor skin infections, such as pimples and abscesses, Toxic shock syndrome, through to septicaemia and pneumonia. It is most widely known as a major cause of hospital acquired infections, and is a frequent cause of post-surgical wound infections. This situation is exacerbated by the fact that some strains of S. aureus are resistant to many antibiotics (e.g. Methicillin Resistant Staphylococcus aureus; MRSA), making it a severe and difficult to treat problem. An understanding, at the molecular level, of S. aureus biology and pathogenesis is essential if we are to design new treatments to prevent or cure infection.Our preliminary work and results from others has suggested that the Ess transport system drives the secretion of at least five different proteins from S. aureus, and it is known that when this system is inactivated S. aureus shows a dramatic reduction in its ability to cause infection. We seek knowledge of the architecture and function of this distinctive bacterial secretion machine and to determine the function of one of the secreted proteins.In order to secrete proteins, the machine needs to be energised. It is very likely that the EssC protein is responsible for providing the energy for this process, by breaking down an energy-rich compound in the cell called ATP. We want to understand the molecular basis for how the machine works. We have significant progress towards this by purifying and crystallising a large part of the EssC protein. We now wish to exploit single crystal X-ray diffraction methods to derive an accurate molecular structure for EssC. We want to build on this by understanding how EssC binds and hydrolyses ATP, and which other proteins in the Ess machine it interacts with.We want to confirm our preliminary results to determine which proteins are secreted by this machine. We would like to determine molecular structures for one of these proteins to understand how they work. Finally we want to understand how these proteins are secreted by the machinery in particular to see if they interact with EssC during their export.Knowing the structures of the protein components and how they interact with each other is important because this might, in the longer term, lay the foundation for studies directed to the design or discovery of compounds that will prevent these proteins from working with each other or prevent the motive force from being used to secrete out the proteins that establish and prolong infection. Information on proteins that are secreted and of the structures found on the surface of the bacterium may also provide opportunities for vaccine design.