Molecular recognition in the streptavidin-biotin system

链霉亲和素-生物素系统中的分子识别

• 批准号: 7336305
• 负责人: TERRY P LYBRAND
• 金额: $ 31.28万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-06-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7336305
• 关键词: Affinity; Behavior; Binding; Binding Proteins; Binding Sites; Biological Models; Biology; Biotin; Characteristics; Complex; Covalent Interaction; Dissociation; Drug Design; Equilibrium; Free Energy; Lead; Ligand Binding; Ligands; Measurement; Mutation; Play; Proteins; Reaction; Resolution; Role; Streptavidin; Structure; System; Temperature; Testing; Thermodynamics; Water; base; biotin-streptavidin complex; concept; design; molecular dynamics; molecular recognition; mutant; simulation

DESCRIPTION (provided by applicant): The streptavidin/biotin complex involves one of the strongest non-covalent interactions observed in biology, and is an ideal model system for the study of high-affinity protein/ligand interactions. Analysis of high- resolution crystal structures for the streptavidin/biotin complex reveals numerous favorable protein-ligand contacts characteristic of a tightly bound complex. However, our extensive structural and thermodynamic characterization of numerous streptavidin mutants strongly suggests that direct protein-ligand contacts cannot fully explain the extremely tight biotin binding. Our previous studies also suggest that biotin follows a well defined reaction coordinate during ligand binding and dissociation reactions, and that certain mutations can alter the activation energy barrier for the binding/dissociation reactions, without any significant effect on the equilibrium structure. These results lead us to propose that streptavidin equilibrium dynamics, or structural fluctuations, help determine the equilibrium binding energy and activation energy barrier. We will test this hypothesis by performing molecular dynamics simulations and detailed crystallographic analyses of anisotropic temperature factors for wild-type and selected mutant streptavidin/biotin complexes, and then look for correlations between structural fluctuations and calorimetric measurements in wild-type versus mutant complexes. Our previous results also suggest that specific water molecules play a key energetic role in the biotin binding/dissociation reactions. We will use molecular dynamics simulations to test this proposal by further characterizing water interactions in the streptavidin binding site. We will use these simulation results to suggest mutations that can alter the equilibrium water behavior in the complex, and thus modulate the ligand binding free energy and/or activation energy. These studies will enhance our understanding of high-affinity protein/ligand binding interactions, and will help us elucidate important concepts that should be useful in structure-based ligand design projects. Such information will be helpful in rational drug design applications for therapeutically important protein targets.

描述（由申请人提供）：链霉亲和生物素复合物涉及在生物学中观察到的最强的非共价相互作用之一，并且是研究高亲和力蛋白/配体相互作用的理想模型系统。分析链霉亲和生物素络合物的高分辨率晶体结构揭示了紧密结合的复合物的许多有利的蛋白质 - 配体接触特征。然而，我们对众多链霉亲和素突变体的广泛结构和热力学表征强烈表明，直接的蛋白质 - 配体接触无法完全解释极度紧密的生物素结合。我们先前的研究还表明，生物素在配体结合和解离反应过程中遵循明确定义的反应坐标，并且某些突变可以改变结合/解离反应的活化能屏障，而对平衡结构没有任何显着影响。这些结果使我们提出链霉亲和素平衡动力学或结构波动有助于确定平衡结合能和激活能屏障。我们将通过进行分子动力学模拟以及对野生型和选定的突变体链霉亲和生物素复合物的各向异性温度因子的详细晶体学分析来检验该假设，然后在野生型突变体中寻找结构波动和量热测量值之间的结构波动与量热仪之间的摩擦。我们先前的结果还表明，特定的水分子在生物素结合/解离反应中起关键的能量作用。我们将使用分子动力学仿真来测试该建议，通过进一步表征链霉亲和素结合位点中的水相互作用。我们将使用这些仿真结果提出可以改变复合物中平衡水行为的突变，从而调节配体结合自由能和/或活化能。这些研究将增强我们对高亲和力蛋白/配体结合相互作用的理解，并将有助于我们阐明在基于结构的配体设计项目中应该有用的重要概念。这些信息将有助于用于治疗上重要蛋白质靶标的合理药物设计应用。