Von Willebrand factor-A1 domain binds platelet glycoprotein Ibα in multiple states with distinctive force-dependent dissociation kinetics.
Von Willebrand factor-A1 domain binds platelet glycoprotein Ibα in multiple states with distinctive force-dependent dissociation kinetics.
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Von Willebrand因子-A1结构域在具有独特的力依赖性解离动力学的多个状态下结合了血小板糖蛋白IBα。
DOI：
10.1016/j.thromres.2015.06.019
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发表时间：
2015-09
影响因子：
7.5
通讯作者：
Zhu C
中科院分区：
文献类型：
--
作者：
Ju L;Chen Y;Zhou F;Lu H;Cruz MA;Zhu C
循环血管性血友病因子 (VWF) 采用封闭构象，屏蔽 VWF-A1 结构域中的血小板糖蛋白 Ibα (GPIbα) 结合位点。 VWF 固定在血管损伤部位，通过与胶原蛋白的相互作用以及增加的血流动力学作用而被激活。对天然 VWF 字符串和分离的 A1 结构域的研究表明，在不同的生物物理环境中存在多种 A1 结合状态。在这项单分子研究中，我们使用生物膜力探针 (BFP) 和流动室来识别和表征与血小板 GPIbα 具有更高亲和力的胶原蛋白结合诱导构象。随着力的增加，我们的结果表明胶原蛋白的结合增加了 GPIbα 与 VWF 和分离的 A1 结构域结合的稳定性。然而，VWF-A3 结构域的胶原蛋白 2D 结合亲和力是 A1 结构域的 10 倍，表明最初的 VWF 捕获是由 A3-胶原蛋白相互作用介导的，而 A1-胶原蛋白调节随后的 VWF 激活。我们的结果揭示了胶原调节、A1 介导的血小板粘附增强的分子机制。不同 A1 状态的表征可以深入了解 VWF 在不同炎症和血栓形成情况下的结合异质性。
Circulating von Willebrand factor (VWF) adopts a closed conformation that shields the platelet glycoprotein Ibα (GPIbα) binding site in the VWF-A1 domain. Immobilized at sites of vascular injury, VWF is activated by its interaction with collagen and the exertion of increased hemodynamic forces. Studies on native VWF strings and isolated A1 domains suggest the existence of multiple A1 binding states in different biophysical contexts. In this single-molecule study, we have used a biomembrane force probe (BFP) and a flow chamber to identify and characterize a collagen binding induced conformation with a higher affinity to platelet GPIbα. As force increases, our results show that collagen binding increases the stability of GPIbα bond with both VWF and isolated A1 domain. However, the collagen 2D binding affinity for VWF-A3 domain is 10 times of that for A1 domain, suggesting the initial VWF capture is mediated by A3–collagen interaction while A1–collagen regulates the subsequent VWF activation. Our results revealed the molecular mechanism of collagen-regulated, A1-mediated platelet adhesion enhancement. Characterization of different A1 states provides insights into binding heterogeneity of VWF in different scenarios of inflammation and thrombosis.