Department of Haematology, Imperial College London, London, UK.
Blood. 2010 Jun 10;115(23):4910-3. doi: 10.1182/blood-2009-12-257949. Epub 2010 Mar 30.
The von Willebrand factor (VWF) A2 crystal structure has revealed the presence of a rare vicinal disulfide bond between C1669 and C1670, predicted to influence domain unfolding required for proteolysis by ADAMTS13. We prepared VWF A2 domain fragments with (A2-VicCC, residues 1473-1670) and without the vicinal disulfide bond (A2-DeltaCC, residues 1473-1668). Compared with A2-DeltaCC, A2-VicCC exhibited impaired proteolysis and also reduced binding to ADAMTS13. Circular dichroism studies revealed that A2-VicCC was more resistant to thermal unfolding than A2-DeltaCC. Mutagenesis of C1669/C1670 in full-length VWF resulted in markedly increased susceptibility to cleavage by ADAMTS13, confirming the important role of the paired vicinal cysteines in VWF A2 domain stabilization.
血管性血友病因子(VWF)A2 晶体结构揭示了 C1669 和 C1670 之间存在罕见的毗邻二硫键,据预测该毗邻二硫键会影响 ADAMTS13 进行蛋白水解所需的结构域展开。我们制备了具有毗邻二硫键(A2-VicCC,残基 1473-1670)和没有毗邻二硫键(A2-DeltaCC,残基 1473-1668)的 VWF A2 结构域片段。与 A2-DeltaCC 相比,A2-VicCC 的蛋白水解作用受损,与 ADAMTS13 的结合也减少。圆二色性研究表明,A2-VicCC 比 A2-DeltaCC 更能抵抗热变性。全长 VWF 中 C1669/C1670 的突变导致对 ADAMTS13 的切割敏感性显著增加,证实了配对毗邻半胱氨酸在 VWF A2 结构域稳定中的重要作用。