STRUCTURAL BASIS OF LIGAND RECOGNITION BY VWF A DOMAINS

VWF A 域配体识别的结构基础

• 批准号: 6167674
• 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/6167674
• 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“I”结构域，如其在整联蛋白中通常所称，是存在于参与细胞-细胞和细胞-基质粘附的许多蛋白质中的约200个残基的蛋白质识别模块。 在大多数测试情况下，母体分子的关键配体结合特性被重组A结构域概括，表明该结构域是粘附功能中的关键元件。 这反过来表明，A结构域是一个有吸引力的治疗药物，将破坏异常粘附的目标。 我们以前已经确定了这个家庭的四个成员的晶体结构，并提出了一个一般的配体识别模型，涉及上表面的域。 在整合素中，金属离子位于推定的配体结合界面，我们称之为“金属离子依赖性粘附位点”或MIDAS基序。此外，我们已经提出，A结构域的构象依赖于A结构域内的三级结构变化（“形状改变”），其产生高亲和力配体结合表面，其中结构域从“闭合”构象转变为“开放”构象。 现在，我们希望测试和扩展这些假设，通过确定晶体结构的A域与它们的配体复合。具体而言，我们将靶向整合素α 1和α 2 I结构域和血管性血友病因子A3结构域与三螺旋胶原样肽的复合物;整合素α M I结构域与纤维蛋白原和ICAM-1片段的复合物;整合素α 2 I结构域与层粘连蛋白片段的复合物;以及血管性血友病因子A1结构域与糖蛋白Ib片段和蛇毒素肉毒素的复合物。 这些目标的一系列成功的结构测定将使我们能够解决以下问题：什么是A/I结构域家族的配体识别的共同和独特的功能？ 金属桥是整合素-配体接触的一般特征吗？ 什么取代了vWF A结构域中的金属？ 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暗示了设计小分子的策略，这些小分子将模拟配体结合并破坏粘附？