Folding and insertion of a bacterial inner-membrane protein

所有的细胞都被脂质膜包围，脂质膜的作用是将细胞内部内容物与细胞外环境分开。嵌入这些膜中的蛋白质就像看门人一样，控制着细胞间物质、信息和能量的流动。当这些蛋白质功能正常时，它们对细胞的健康至关重要，然而，这些蛋白质的特定缺陷与许多已知的疾病状态有关。因此，膜蛋白成为药物开发的主要靶点并不奇怪，目前市场上大约60%的药物都针对这些蛋白质起作用。尽管与可溶性蛋白相比，任何生物体大约有三分之一的基因组编码膜蛋白，但人们对膜蛋白的结构和功能知之甚少。事实上，到目前为止，所有高分辨率结构中只有不到1%是膜蛋白结构。阐明这些蛋白是如何合成的，以及哪些因素决定了它们的准确靶向和插入到正确的膜中，将极大地帮助我们了解这些蛋白，并将产生关于它们的结构/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的折叠，从其合成的最早阶段，当它仍然包含在核糖体中，直到它完全融入其目的膜。更具体的研究目的是：1。研究细菌膜蛋白被核糖体制造时的折叠。二次构造形成的时间和位置对其与瞄准和插入机械的相互作用至关重要。2. 研究核糖体或细胞质内的哪些其他蛋白质帮助新合成的蛋白质向膜移动。3. 研究膜插入酶的结构，了解它是如何促进蛋白质插入的。4. 研究膜蛋白与靶膜接触并最终插入时结构的变化

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