Chen Po-Chia, Kutzki Fabian, Mojzisch Angelika, Simon Bernd, Xu Emma-Ruoqi, Aponte-Santamaría Camilo, Horny Kai, Jeffries Cy, Schneppenheim Reinhard, Wilmanns Matthias, Brehm Maria A, Gräter Frauke, Hennig Janosch
Structural and Computational Biology Unit, EMBL Heidelberg, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.
J Struct Biol. 2022 Dec;214(4):107923. doi: 10.1016/j.jsb.2022.107923. Epub 2022 Nov 18.
Von Willebrand disease (VWD) is a bleeding disorder with different levels of severity. VWD-associated mutations are located in the von Willebrand factor (VWF) gene, coding for the large multidomain plasma protein VWF with essential roles in hemostasis and thrombosis. On the one hand, a variety of mutations in the C-domains of VWF are associated with increased bleeding upon vascular injury. On the other hand, VWF gain-of-function (GOF) mutations in the C4 domain have recently been identified, which induce an increased risk of myocardial infarction. Mechanistic insights into how these mutations affect the molecular behavior of VWF are scarce and holistic approaches are challenging due to the multidomain and multimeric character of this large protein. Here, we determine the structure and dynamics of the C6 domain and the single nucleotide polymorphism (SNP) variant G2705R in C6 by combining nuclear magnetic resonance spectroscopy, molecular dynamics simulations and aggregometry. Our findings indicate that this mutation mostly destabilizes VWF by leading to a more pronounced hinging between both subdomains of C6. Hemostatic parameters of variant G2705R are close to normal under static conditions, but the missense mutation results in a gain-of-function under flow conditions, due to decreased VWF stem stability. Together with the fact that two C4 variants also exhibit GOF characteristics, our data underline the importance of the VWF stem region in VWF's hemostatic activity and the risk of mutation-associated prothrombotic properties in VWF C-domain variants due to altered stem dynamics.
血管性血友病（VWD）是一种严重程度各异的出血性疾病。与VWD相关的突变位于血管性血友病因子（VWF）基因中，该基因编码一种大型多结构域血浆蛋白VWF，其在止血和血栓形成中起关键作用。一方面，VWF C结构域中的多种突变与血管损伤后出血增加有关。另一方面，最近发现了C4结构域中的VWF功能获得性（GOF）突变，其会增加心肌梗死的风险。关于这些突变如何影响VWF分子行为的机制见解很少，并且由于这种大蛋白的多结构域和多聚体特性，整体研究方法具有挑战性。在这里，我们通过结合核磁共振光谱、分子动力学模拟和凝集分析，确定了C6结构域的结构和动力学以及C6中的单核苷酸多态性（SNP）变体G2705R。我们的研究结果表明，这种突变主要通过导致C6的两个亚结构域之间更明显的铰链作用而使VWF不稳定。在静态条件下，变体G2705R的止血参数接近正常，但由于VWF茎稳定性降低，错义突变在流动条件下导致功能获得。再加上两个C4变体也表现出GOF特征这一事实，我们的数据强调了VWF茎区域在VWF止血活性中的重要性，以及由于茎动力学改变，VWF C结构域变体中与突变相关的血栓前特性的风险。
