Biogenesis of a respiratory complex essential for viability of pathogenic Mycobacteria

地球上的大多数生物都需要氧气才能生存。这不仅适用于动物，也适用于细菌，它支持一种被称为呼吸作用的基本过程。在呼吸过程中，电子(来自葡萄糖等食物)被用来将氧气还原为水。这一过程发生在细胞膜内，并由嵌入细胞膜中的蛋白质进行。这些蛋白质接受来自葡萄糖的电子，并将它们沿着链传递，在链的末端，氧被还原，水形成。电子转移链的重要组成部分之一是三种相互作用的蛋白质，统称为细胞色素Bc1复合体。这个复合体的三个蛋白质中的每一个都结合了一个金属辅因子，可以接受电子并将它们传递给链中的下一个蛋白质。我们对细胞色素Bc1复合体的一种蛋白质感兴趣，这种蛋白质被称为Rieske蛋白。这种蛋白质含有一种特殊类型的辅因子，称为铁硫簇，它是蛋白质传递电子所必需的。我们发现，引起致命疾病结核病的病原体结核分枝杆菌和其他一些密切相关的细菌的Rieske蛋白是不寻常的，因为它比预期的要大得多。这意味着这些细菌中的Rieske蛋白必须以不同于所有其他生命形式的Rieske蛋白的方式插入膜中。我们想了解这些更大的Rieske蛋白是如何制造的。除此之外，我们还想找出Rieske蛋白的这一额外部分在做什么，以及是否有必要让这些细菌呼吸氧气。我们这样做的一种方法是移除这一额外的部分，看看它是否会阻止Rieske蛋白的工作。我们做到这一点的另一种方法是，当我们通过阻止Rieske蛋白质正确插入膜来干扰Rieske蛋白质时，检查细胞色素Bc1复合体的组织。最终，我们将在这个项目中所做的工作将使我们从根本上洞察这个蛋白质复合体是如何组装的。我们产生的这种基本知识最终可能被利用来干扰结核分枝杆菌这个重要复合体的组装。

Most of the organisms on earth require oxygen for life. This is not just true for animals, but also for bacteria, and it supports an essential process known as respiration. During respiration electrons (derived from food such as glucose) are used to reduce the oxygen to water. This process happens within the membranes of cells and is carried out by proteins that are found embedded within those membranes. The proteins accept the electrons that derive from glucose and pass them along a chain, at the end of that chain oxygen is reduced and water is formed. One of the essential components of the electron transfer chain is three proteins that interact with each other and is collectively called the cytochrome bc1 complex. Each of the three proteins of this complex binds a metal cofactor that can accept the electrons and pass them on to the next protein in the chain. We are interested in one of the proteins of the cytochrome bc1 complex that is called the Rieske protein. This protein contains a special type of cofactor called an iron sulphur cluster that is essential to allow the protein to transfer electrons. We have discovered that the Rieske protein from the pathogen Mycobacterium tuberculosis, which causes the deadly disease tuberculosis, and some other closely related bacteria is unusual, because it is much bigger than expected. This means that the Rieske protein in these bacteria has to be inserted into the membrane in a different way than the Rieske protein from all other life forms. We would like to understand how these bigger Rieske proteins are made. In addition to this we would like to find out what this extra part of the Rieske protein is doing, and whether it is essential to allow these bacteria to respire oxygen. One way we will do this is to remove this extra part and see if it stops the Rieske protein from working. Another way we will do this is to examine the organisation of the cytochrome bc1 complex when we interfere with the Rieske protein by preventing it from being properly inserted into the membrane.Ultimately the work we will do in this project will give us fundamental insight into how this protein complex is assembled. This basic knowledge that we generate may eventually be exploited to interfere with the assembly of this essential complex in Mycobacterium tuberculosis.