Structure and stability of 3-alpha vs alpha/beta folds

描述(由申请人提供)：破译 蛋白质折叠的编码是折叠信息是分散的。这样做的目的是 建议更好地理解氨基酸序列是如何指定唯一的 通过将折叠问题减少到那些可以 包含有关指定一个折叠与另一个折叠的最多信息。去做 为此，欧尔班博士建议产生和研究一对高含量的蛋白质 序列相同，但三级结构不同。他将学习切换 在α/β结构和三个α-螺旋束结构(3-a)之间作为 氨基酸序列的功能和区分两者的能量的表征 通过各种生物物理方法构象。免疫球蛋白的免疫球蛋白结合区 将使用链球菌蛋白G(GB)和葡萄球菌蛋白A(AB)作为 一双。蛋白G(GA)和GB的白蛋白结合域将被用作 第二对。这三个结构域的大小相似(45-58个氨基酸)。AB GA有3个阿尔法折叠，GB有α/β折叠。噬菌体展示 选择方法将被用来诱导构象转换 3-a结构和α/β结构，同时保持最高 序列同一性的实际水平。然后PI将使用热力学 折叠与免疫球蛋白或白蛋白结合之间的联系以定量折叠 每种氨基酸的信息含量在同源对中不同。一个 将使用包括多维核磁共振在内的各种生物物理技术 探索序列空间的结构和能量性质 同源蛋白质对。更全面地了解如何主要 序列决定了稳定、独特的蛋白质折叠应该会极大地促进 蛋白质工程、蛋白质结构预测和从头蛋白质领域 设计。也可能有这种技术的应用来创造分子 基于蛋白质性质的开关以改变构象作为响应 一种微妙的外部刺激。

DESCRIPTION (provided by applicant): The major difficulty in deciphering the protein folding code is that folding information is diffuse. The aim of this proposal is to better understand how amino acid sequence specifies unique tertiary folds by reducing the folding problem to those amino acids which contain the most information toward specifying one fold versus another. To do this, Dr. Orban proposes to generate and study pairs of proteins with high sequence identity but different tertiary structures. He will study switching between alpha/beta structure and three a-helix bundle structure (3-a) as a function of amino acid sequence and characterize the energy separating the two conformations by a variety of biophysical methods. The IgG-binding domains of streptococcal protein G (GB) and staphylococcal protein A (AB) will be used as one pair. The albumin binding domain of protein G (GA) and GB will be used as the second pair. All three domains are of similar size (45-58 amino acids). AB and GA have 3-alpha folds and GB has an alpha/beta fold. Phage display selection methods will be used to induce a conformational switch between the 3-a structure and the alpha/beta structure, while maintaining the highest practicable level of sequence identity. The PI will then use the thermodynamic linkage between folding and IgG- or albumin-binding to quantitate the folding information content of each amino acid which differs in homologous pairs. A variety of biophysical techniques including, multidimensional NMR, will be used to explore structural and energetic properties of the sequence space between the homologous protein pairs. More complete knowledge concerning how primary sequence determines stable, unique protein folds should greatly advance the fields of protein engineering, protein structure prediction and de novo protein design. There also may be applications of this technology to create molecular switches based on the property of a protein to change conformations in response to a subtle external stimulus.