Four Mtb Membrane Proteins: Structure and Function

描述（由申请人提供）：没有其他病原体比结核分枝杆菌引起的死亡率更高，每年有近200万人死亡。通过在各种膜模拟环境中表征膜蛋白结构的能力，可以大大提高潜在药物靶点的功能知识。膜蛋白代表这些目标的大多数，但只有一个1200推定的膜蛋白在结核分枝杆菌基因组中的特征，只有少数其他人很好地模拟同源性与蛋白质密切相关的物种。在这里，我们建议表征的骨干结构和动力学，并获得机械知识的生物功能的四个重要的膜蛋白从结核分枝杆菌基因组。了解膜蛋白的结构和功能代表了一个重大的科学前沿，是深刻的重要国家和世界的健康。支原体结核病过去几十年来没有新的药物出现，尽管有相当多的潜在药物正在研制中。去年在南非造成53名患者中的52人死亡的广泛耐药结核病现在被认为已经蔓延到非洲大陆的许多贫穷和不发达国家。此外，Mtb的潜伏状态所必需的漫长的药物方案使治疗大大复杂化。因此，了解进入和退出的潜在状态是非常重要的。许多障碍共同阻碍了膜蛋白的结构表征（蛋白质数据库中0.3%的结构对大多数基因组的30%）。与所有的结构方法一样，主要的挑战是样品制备。在过去的一年中，在溶液和固态NMR的这一竞技场中取得了非常重大的进展。不仅样品制备具有挑战性，而且膜蛋白具有多种构象和功能状态，使这些蛋白质的功能理解复杂化，并需要更多的结构工作。此外，它们的动力学更复杂，反映了异质环境;它们形成具有不同分子相互作用平衡的复合物。这四种蛋白质包括CorA，对于这种Mg 2+转运蛋白的闭合状态，已经存在来自海栖热袍菌的晶体结构。我们建议的Mtb跨膜结构域的特点，并开发一个模型的镁离子转运CorA。对于Kdp复合物，我们将重点关注被认为在此K+转运系统中具有协调作用的必需KdpC蛋白。ChiZ被认为是细胞分裂的抑制剂，并且可能是进入潜伏状态的调节剂。Rv 1861似乎是水解ATP并可能与糖基转移酶形成复合物的八聚体蛋白。

DESCRIPTION (provided by applicant): No other pathogen causes more mortality than Mycobacterium tuberculosis with nearly 2 million deaths per year. Through an ability to characterize membrane protein structure in various membrane mimetic environments, functional knowledge of potential drug targets can be greatly advanced. Membrane proteins represent the majority of these targets, yet only one out of 1200 putative membrane proteins in the Mtb genome is characterized and only a few others are well modeled by homology with proteins from closely related species. We propose here to characterize the backbone structure and dynamics and to gain mechanistic knowledge of the biological function of four significant membrane proteins from the Mtb genome. Understanding membrane protein structure and function represents a major scientific frontier that is profoundly important to the Nation's and the World's health. For M. tuberculosis there have been no new drugs in the past few decades although there are quite a few potential drugs in the pipeline. Extensively drug resistant Mtb, which killed 52 of 53 patients in South Africa last year is now thought to have spread to many poor and undeveloped countries on the African continent. Furthermore, the lengthy drug regimen necessitated by the latent state of Mtb greatly complicates treatment. Therefore, understanding entry and exit from the latent state is very important. Many obstacles have conspired to impede the structural characterization of membrane proteins (0.3% of the structures in the Protein Data Bank versus 30% of most genomes). As with all of the structural methods the primary challenge has been in sample preparation. Over the past year very significant progress has been made in this arena for solution and solid-state NMR. Not only is sample preparation challenging, but membrane proteins have multiple conformational and functional states complicating the functional understanding of these proteins and necessitating more structural work. In addition, their dynamics is more complex reflecting a heterogeneous environment; and they form complexes with a different balance of molecular interactions. These four proteins include CorA for which there is already a crystal structure from Thermatoga maritima for the closed state of this Mg2+ transporter. We propose to characterize the Mtb transmembrane domain and develop a model for Mg2+ transport by CorA. For the Kdp complex we will focus on the essential KdpC protein that is thought to have a coordinating role in this K+ transport system. ChiZ is thought to be an inhibitor of cell division and potentially a regulator of entry into the latent state. Rv1861 appears to be a octameric protein that hydrolyzes ATP and potentially forms a complex with a glycosyltransferase.