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X-ray crystallographic studies of the TatBC complex - linchpin of the twin-arginine protein transport system

TatBC 复合体的 X 射线晶体学研究 - 双精氨酸蛋白转运系统的关键

基本信息

批准号：
BB/E023347/1
负责人：
Benjamin Berks
金额：
$ 48.35万
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FE023347%2F1
关键词：
ray crystallographic studies TatBC complex

项目摘要

Some bacterial proteins operate on the outside of the cell, for example the toxins produced by bacterial pathogens. Since all proteins are made inside the bacterium the extracellular proteins must be moved out of the cell across the normally impermeable cell membrane. This task is carried out by machines termed protein transporters that are located in the cell membrane. One type of transporter moves unfolded proteins, threading them across the membrane like string through the eye of a needle. By contrast, a second type of transporter, which we term the Tat system, moves folded proteins across the membrane. This is much more challenging than threading and so it is thought that the Tat system operates by an unusual mechanism. The Tat protein transport system is not only found in bacteria it is also present in the chloroplasts of plants where it is essential to form and maintain the proteins required to carry out photosynthesis. The heart of the Tat system is a complex formed by two proteins called TatB and TatC. This complex sits in the cell membrane and recognises and binds the proteins that are to be transported. It then binds another protein called TatA to form the active transporter. We aim to determine a detailed structure of the complex containing TatB and TatC. We will also try to determine the structure of TatC alone since this may be easier and TatC appears to form the stable functional core of the Tat system. To obtain these structures we first need to grow crystals of the purified proteins. This is likely to be quite challenging because it is not easy to form crystals of proteins found in membranes. For this reason we have proposed a number or different crystallization approaches to maximize our chances of success. We will also make full use of the latest high-throughput technologies to speed the work. Determination of a structure for TatBC and/or TatC is essential if we are to understand the unusual mechanism of transport by the Tat system. The Tat system is a possible drug target because it is required for bacterial pathogenesis but is not found in humans. It is also of biotechnological interest because it could be utilised to secrete useful protein products.

一些细菌蛋白质在细胞外部起作用，例如细菌病原体产生的毒素。由于所有的蛋白质都是在细菌内部制造的，因此胞外蛋白质必须穿过通常不可渗透的细胞膜移出细胞。这一任务是由位于细胞膜上的蛋白质转运蛋白完成的。一种类型的转运蛋白移动未折叠的蛋白质，将它们穿过细胞膜，就像穿过针眼的线一样。相比之下，第二种类型的转运蛋白，我们称之为达特系统，将折叠的蛋白质跨膜移动。这比线程化更具挑战性，因此人们认为达特系统通过一种不寻常的机制运行。达特蛋白转运系统不仅存在于细菌中，它也存在于植物的叶绿体中，在那里它是形成和维持进行光合作用所需的蛋白质所必需的。达特系统的核心是由两种称为TatB和TatC的蛋白质形成的复合物。这种复合物位于细胞膜中，识别并结合要运输的蛋白质。然后，它结合另一种称为TatA的蛋白质，形成活性转运蛋白。我们的目标是确定含有TatB和TatC的复合物的详细结构。我们还将尝试单独确定TatC的结构，因为这可能更容易，并且TatC似乎形成达特系统的稳定功能核心。为了获得这些结构，我们首先需要生长纯化蛋白质的晶体。这可能是相当具有挑战性的，因为在膜中发现的蛋白质不容易形成晶体。出于这个原因，我们提出了一些或不同的结晶方法，以最大限度地提高我们的成功机会。我们还将充分利用最新的高通量技术来加快工作速度。如果我们要理解达特系统的不寻常的运输机制，那么确定TatBC和/或TatC的结构是必不可少的。达特系统是一个可能的药物靶点，因为它是细菌致病所必需的，但在人类中没有发现。它也是生物技术的兴趣，因为它可以用来分泌有用的蛋白质产品。