Bioorganic models for transmembrane proteins

描述（由申请人提供）：自从Anfinsen证明了蛋白质的序列决定了它的结构，折叠的能量学和动力学已经以越来越高的时间和空间分辨率进行了探索。然而，几乎所有这些研究都致力于水溶性蛋白，我们对膜蛋白的理解还处于起步阶段。在这里，我们使用蛋白质设计来测试和完善我们对膜蛋白折叠的理解。模型肽被设计成胶束和磷脂双分子层中的螺旋束。这些体系的展开态（单体螺旋）是明确的，并且可以通过测量单体-单体平衡来监测折叠的能量学，从而简化了对这些体系的研究。在目标1和2中，我们测试了不同力的重要性和相对能量贡献，如范德华填料与极性相互作用。这些研究不仅将进一步加深我们对蛋白质折叠的理解，而且还将为理解在信号转导中起重要作用的跨膜螺旋关联过程提供见解和方法。由于我们对膜蛋白折叠的理解，我们开始设计两种膜蛋白的水溶性版本，磷蛋白和KcsA钾通道。这些研究有望为获得大量水溶性膜蛋白提供一种新的方法，用于制药和生物物理研究。我们的具体目标如下：目标1。我们将研究设计和天然跨膜肽的关联，并使用这些系统来了解导致跨膜螺旋折叠和关联的特征。目标2。我们将通过设计包含跨膜和水溶性折叠基序的螺旋束，探索位于水、头基和膜内部的蛋白质区域如何合作来决定蛋白质的折叠。目的3：我们将对磷蛋白和KcsA的水溶性版本进行结构表征。Aim4。我们将开发跨膜蛋白质结构预测和设计的计算方法。

DESCRIPTION (provided by applicant): Since Anfinsen's demonstration that the sequence of a protein dictates its structure, the energetics and kinetics of folding have been explored with ever-greater temporal and spatial resolution. However, almost all of these studies have been devoted to water-soluble proteins, and our understanding of membrane proteins is in its infancy. Here, we use protein design to test and refine our understanding of membrane protein folding. Model peptides are designed to associate into helical bundles in micelles and phospholipid bilayers. The study of these systems is simplified by the fact that the unfolded state is well defined (the monomeric helices), and the energetics of folding can be monitored by measuring the monomer-nmer equilibrium. In aims 1 & 2, we test the importance and relative energetic contributions of disparate forces such as van der Waals packing versus polar interactions. These studies will not only further our understanding of protein folding, but also provide insight and methods to understand the process of transmembrane helix association, which often plays an essential role in signal transduction. As an outgrowth of our understanding of the folding of membrane proteins, we are beginning to design water-soluble versions of 2 membrane proteins, phospholamban and the KcsA potassium channel. These studies promise to provide a new method for obtaining large quantities of water-soluble versions of membrane proteins for pharmaceutical and biophysical studies. Our specific aims are as follows: Aim 1. We will study the association of designed and natural transmembrane peptides, and use these systems to understand the features leading to the folding and association of transmembrane helices. Aim 2. We will explore how regions of a protein located in the aqueous, headgroup, and membrane interior cooperate to dictate the fold of a protein by designing helical bundles that incorporate both transmembrane as well as water-soluble folding motifs. Aim 3 We will structurally characterize water-soluble versions of phospholamban and KcsA. Aim4. We will develop computational methods for transmembrane protein structure prediction & design.