Folding and dynamics of membrane proteins and HIV-1 Tat

所有的细胞及其细胞器都被一层膜包围着。嵌入细胞膜中的蛋白质通道和受体精确地控制着营养物质、废物、能量甚至信息进出细胞和细胞器的流动。膜蛋白占所有细胞蛋白的20-30%，未来药物开发的所有靶点可能有50%是膜蛋白，但所有已知蛋白质结构中只有1.6%属于膜蛋白。了解膜蛋白的分子结构和动力学对于理解细胞生物学和医学中许多基本过程的功能是必不可少的。我们的长期目标是开发方法来克服膜蛋白结构和动力学测定中的许多困难。近年来，我们在研究细菌膜蛋白甘油促进剂的结构和折叠方面取得了一些进展。我们建议通过开发我们的系统来继续这项工作，核磁共振（NMR）光谱，一种类似于磁共振成像的方法。一旦开发成功，我们将把我们的方法应用于其他膜受体的研究，如介导冷热感觉的温度敏感受体。人们认为它们的功能是由其结构的变化决定的，核磁共振特别适合于蛋白质动力学的测量。我们还将继续研究真菌抗生素肽alamethicin，这是一种模型膜蛋白。HIV-1转录反激活因子（Tat）是一种小的人类免疫缺陷病毒蛋白，在调节HIV-1复制、HIV-1潜伏期、免疫抑制和艾滋病相关痴呆中起关键作用。我们最近制备了Tat蛋白，并通过核磁共振对其结构和动力学进行了研究。我们发现这种蛋白质是天然展开的，这有助于解释为什么它可以与如此广泛的蛋白质相互作用。我们建议研究Tat与另一种在大多数细胞中发现的称为钙调蛋白的蛋白质结合的结构。了解Tat结合的分子基础将有助于更好地了解其在HIV-1感染中的作用，并可能为改进治疗提供基础。

All cells and their organelles are surrounded by a membrane. Protein channels and receptors that are embedded in membranes precisely control the flow of nutrients, waste products, energy, and even information into and out of cells and organelles. Membrane proteins comprise 20-30% of all cellular protein and it is likely that 50% of all future targets for drug development will be membrane proteins, yet only 1.6% of all known protein structures belong to membrane proteins. Knowledge of the molecular structures and dynamics of membrane proteins is essential for understanding the functioning of many basic processes in cell biology and medicine. Our long-term goal is to develop methods to overcome the many difficulties in membrane protein structure and dynamics determination. Recently, we have made progress in studying the structure and folding of a bacterial membrane protein, the glycerol facilitator. We propose to continue this work by developing our system for investigation by Nuclear Magnetic Resonance (NMR) spectroscopy, a method analogous to Magnetic Resonance Imaging.  Once developed, we will apply our methods to the study of other membrane receptors such as the temperature-sensitive receptors that mediate the senses of hot and cold. It is thought that their function is determined by changes in their structures and NMR is particularly well suited to the measurement of protein dynamics. We will also continue our work on the fungal antibiotic peptide alamethicin that is a model membrane protein. HIV-1 Transactivator of transcription (Tat) is a small Human Immunodeficiency Virus protein that is a key player in the regulation of HIV-1 replication, HIV-1 latency, immune suppression, and AIDS-related dementia. We have recently prepared Tat protein and studied its structure and dynamics by NMR. We have found that the protein is natively unfolded which helps to explain why it can interact with such a wide variety of proteins. We propose to study the structure of Tat bound to another protein named calmodulin that is found in most cells. Understanding the molecular basis of Tat binding will contribute to a better understanding of its role in HIV-1 infection and may provide the basis of improving therapies.