von Willebrand factor (VWF) is an adhesive glycoprotein that circulates in the blood as disulfide-linked concatemers and functions in primary hemostasis. The loss of long VWF concatemers is associated with the excessive bleeding of type 2A von Willebrand disease (VWD). Formation of the disulfide bonds that concatemerize VWF requires VWF to self-associate into helical tubules, yet how the helical tubules template intermolecular disulfide bonds is not known. Here, we report electron cryomicroscopy (cryo-EM) structures of VWF tubules before and after intermolecular disulfide bond formation. The structures provide evidence that VWF tubulates through a charge-neutralization mechanism and that the A1 domain enhances tubule length by crosslinking successive helical turns. In addition, the structures reveal disulfide states before and after disulfide bond-mediated concatemerization. The structures and proposed assembly mechanism provide a foundation to rationalize VWD-causing mutations.

中文翻译：

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串联前后 VWF 小管的结构揭示了二硫键交换的机制。

冯维勒布兰德因子 (VWF) 是一种粘附糖蛋白，以二硫键连接的多联体形式在血液中循环，并在初级止血中发挥作用。长 VWF 串联体的缺失与 2A 型冯维勒布兰德病 (VWD) 的过度出血有关。与 VWF 串联的二硫键的形成需要 VWF 自缔合成螺旋小管，但螺旋小管如何模板化分子间二硫键尚不清楚。在这里，我们报告了分子间二硫键形成前后 VWF 小管的电子冷冻显微镜 (cryo-EM) 结构。这些结构提供了证据，表明 VWF 通过电荷中和机制进行管状化，并且 A1 结构域通过交联连续的螺旋圈来增加管状长度。此外，这些结构揭示了二硫键介导的多联化之前和之后的二硫键状态。这些结构和拟议的组装机制为合理化 VWD 引起的突变奠定了基础。