STRUCTURAL BASIS OF LIGAND RECOGNITION BY VWF A DOMAINS

VWF A 域配体识别的结构基础

• 批准号: 6387224
• 负责人: ROBERT Colin LIDDINGTON
• 金额: $ 29.25万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2004-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6387224
• 关键词: X ray crystallography; cell adhesion; collagen; conformation; crystallization; fibrinogen; integrins; laminin; ligands; protein structure function; receptor binding; reptile poison; von Willebrand factor

The "A" domain, or "I" domain as it is commonly called in integrins, is a approximately 200 residue protein recognition module that is present in many proteins involved in cell-cell and cell-matrix adhesion. In most cases tested, key ligand binding properties of the parent molecule are recapitulated by recombinant A domains, demonstrating that this domain is a critical element in the adhesion function. This in turn suggests that the A domain is an attractive target for therapeutic agents that would disrupt aberrant adhesion. We have previously determined the crystal structures of four members of this family and proposed a general model for ligand recognition involving the upper surface of the domain. In the integrins, a metal ion is located at the putative ligand binding interface, which we have called the "metal ion-dependent adhesion site" or MIDAS motif. In addition, we have proposed that the adhesiveness of A domains is dependent on tertiary structure changes within the A domain ("shape-shifting") that create a high affinity ligand binding surface, in which the domain switches from a "closed" to an "open conformation. We now wish to test and extend these hypotheses by determining crystal structures of A domains in complex with their ligands. Specifically, we will target complexes of the integrin alpha1 and alpha2 I domains and the von Willebrand Factor A3 domain with triple helical collagen-like peptides; the integrin alphaM I domain with fragments of fibrinogen and ICAM-1; the integrin alpha2 I domain with a fragment of laminin; and the von Willebrand Factor A1 domain with a fragment of glycoprotein lb and the snake toxin botrocetin. Successful structure determination of a range of these targets will enable us to address the following questions: What are the common and distinct features of ligand recognition by the A/I domain family? Is a metal bridge a general feature of integrin-ligand contacts? What replaces the metal in the vWF A domains? Is tertiary "shape- shifting" a common feature of A/I domains, and does this represent a mechanism for regulation? And finally, do our structural data suggest strategies for the design of small molecules that would mimic ligand binding and disrupt adhesion?

“A”结构域，或在整合素中通常被称为“I”结构域，是一个大约200个残基蛋白识别模块，存在于许多参与细胞-细胞和细胞-基质粘附的蛋白质中。在大多数测试中，母体分子的关键配体结合特性通过重组A结构域重现，表明该结构域是粘附功能的关键因素。这反过来表明A结构域是治疗药物的一个有吸引力的靶标，可以破坏异常粘附。我们之前已经确定了这个家族的四个成员的晶体结构，并提出了一个涉及结构域上表面的配体识别的一般模型。在整合素中，一个金属离子位于假定的配体结合界面，我们称之为“金属离子依赖的粘附位点”或MIDAS基序。此外，我们提出了A结构域的粘附性取决于A结构域内三级结构的变化（“形状变化”），这种变化会产生高亲和力的配体结合表面，其中结构域从“封闭”构象切换到“开放”构象。我们现在希望通过确定A域及其配体的晶体结构来测试和扩展这些假设。具体来说，我们将用三螺旋胶原样肽靶向整合素α 1和α 2 I结构域和血管性血液病因子A3结构域的复合物；带纤维蛋白原和ICAM-1片段的整合素α -1结构域；带层粘连蛋白片段的整合素α 2 I结构域；血管性血友病因子A1结构域含有糖蛋白lb片段和蛇毒肉素。成功确定一系列这些靶点的结构将使我们能够解决以下问题：a /I结构域家族的配体识别的共同和独特特征是什么？金属桥是整合素-配体接触的普遍特征吗？什么取代了vWF域中的金属？三级“变形”是a /I结构域的共同特征吗？这是否代表了一种调节机制？最后，我们的结构数据是否为设计模拟配体结合和破坏粘附的小分子提供了策略？