Folding and insertion of a bacterial inner-membrane protein

所有细胞都被脂质基膜包围，这些膜起到将细胞内部内容物与细胞外环境分开的作用。嵌入在这些膜中的蛋白质充当守门人，控制着细胞之间的物质、信息和能量的流动。当这些蛋白质正常运作时，它们对细胞的健康至关重要，然而，这些蛋白质中的特定缺陷与许多已知的疾病状态有关。因此，膜蛋白是药物开发的主要靶点也就不足为奇了，目前市场上大约60%的药物对这些蛋白起作用。尽管任何生物体基因组的大约三分之一编码膜蛋白，但相对于可溶性蛋白，人们对其结构和功能知之甚少。事实上，到目前为止，所有高分辨结构中只有不到1%是膜蛋白的结构。阐明这些蛋白质是如何合成的，以及是什么因素决定了它们的准确靶向和插入正确的膜，这将极大地帮助我们理解这些蛋白质，并产生关于它们结构/功能关系的新信息，这可能有助于设计更好、更有效的药物。这一建议旨在了解膜蛋白从合成的最早阶段起的折叠过程，当时它仍然包含在核糖体中，直到它完全整合到目的细胞膜中。这项研究的更具体的目的是：1。研究细菌膜蛋白在核糖体制造时的折叠。二级结构形成的时间和位置将对其与靶向和插入机械的相互作用至关重要。2.研究核糖体或细胞质中的哪些其他蛋白质有助于新合成的蛋白质进入细胞膜。3.研究膜插入酶的结构，以了解它如何发挥促进蛋白质插入的功能。4.研究膜蛋白与其靶膜接触并最终插入时的结构变化

All cells are surrounded by lipid based membranes which act to separate the cells internal contents from the extra cellular environment. Proteins embedded in these membranes act as gate keepers, controlling the flow of materials, information and energy between cells. When these proteins are functioning normally they are vital to the health of the cell, however specific defects in these proteins are associated with many known disease states. As such it is not surprising that membrane proteins are a major target for drug development and approximately 60% of all drugs on the market today act against these proteins. Although approximately one third of the genome of any organism encodes membrane proteins, relative to soluble proteins, very little information is know about their structures and functions. In fact less than 1% of all high resolution structures solved to date are those of membrane proteins. The elucidation of more information about how these proteins are synthesized and what factors determine their accurate targeting and insertion into the correct membrane will greatly aid our understanding of these proteins and will yield new information about their structure/function relationship, which may help in the design of better more effective drugs. This proposal is directed towards understanding the folding of a membrane protein from the earliest stage of its synthesis, when it is still contained within the ribosome, until it is fully integrated into its destination membrane. The more specific aims of the study are: 1. To study the folding of a bacterial membrane protein as it is being made by the ribosome. The time and location of the secondary structure formation will be critical to its interaction with targeting and insertion machinery. 2. To investigate which other proteins either within the ribosome or the cell cytoplasm aid the newly synthesized protein in travelling to the membrane. 3. To study the structure of the membrane insertase to see how it functions to facilitate protein insertion. 4. To investigate changes in the structure of the membrane protein as it comes into contact with its target membrane and is ultimately inserted