STRUCTURAL BASIS OF LIGAND RECOGNITION BY VWF A DOMAINS

VWF A 域配体识别的结构基础

• 批准号: 6520312
• 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/6520312
• 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，或在整联蛋白中通常称为“I”结构域，是一个大约 200 个残基的蛋白质识别模块，存在于许多涉及细胞-细胞和细胞-基质粘附的蛋白质中。 在大多数测试情况下，重组 A 结构域重现了母体分子的关键配体结合特性，证明该结构域是粘附功能的关键元件。 这反过来表明 A 结构域是破坏异常粘附的治疗药物的一个有吸引力的靶点。 我们之前已经确定了该家族四个成员的晶体结构，并提出了涉及域上表面的配体识别的通用模型。 在整合素中，金属离子位于假定的配体结合界面，我们将其称为“金属离子依赖性粘附位点”或 MIDAS 基序。此外，我们提出A结构域的粘附性取决于A结构域内的三级结构变化（“变形”），从而产生高亲和力的配体结合表面，其中结构域从“封闭”构象转变为“开放构象”。我们现在希望通过确定A结构域与其配体复合物的晶体结构来测试和扩展这些假设。具体来说，我们将靶向整联蛋白的复合物 α1 和 α2 I 结构域以及冯维勒布兰德因子 A3 结构域以及三螺旋胶原蛋白样肽；整合素 alphaM I 结构域及纤维蛋白原和 ICAM-1 片段；整合素 α2 I 结构域和层粘连蛋白片段；以及带有糖蛋白 lb 片段和蛇毒素的冯维勒布兰德因子 A1 结构域 波罗西丁。 成功确定一系列这些靶标的结构将使我们能够解决以下问题：A/I 结构域家族配体识别的共同和独特特征是什么？ 金属桥是整合素-配体接触的一般特征吗？ 什么取代了 vWF A 域中的金属？ 三级“变形”是A/I域的共同特征吗？这是否代表一种调节机制？ 最后，做我们的 结构数据表明了模拟配体结合并破坏粘附的小分子设计策略？