Crystal structure analysis for the pathogenesis of thrombosis

ADAMTS-13基因中的P475 S多态性导致血浆VWF裂解活性降低。为了证明这种突变的影响，我们确定了ADAMTS 13-DTCS的P475 S突变体（DTCS-P475 S）的晶体结构和MDTCS-P475 S的酶参数。结构分析表明，DTCS-P475 S的V环构象发生了明显的变化，没有观察到Ser 475与其他残基的明显相互作用。MDTCS-P475 S显示出与野生型MDTCS相似的反应速率，但显示出对肽基底物的两倍低的亲和力。MDTCS-P475 S可以适度切割剪切处理的VWF。我们已经提供了结构证据，表明ADAMTS-13中的P475 S多态性导致局部结构不稳定性增加，导致对底物的亲和力降低而不改变反应速率。ADAMTS-13-P475 S对剪切处理的VWF的中等活性足以预防血栓性血小板减少性紫癜发作。

A P475S polymorphism in the ADAMTS-13 gene causes an reduction in plasma VWF-cleaving activity. To demonstrate the impact of this mutation, we determined the crystal structure of the P475S mutant of ADAMTS13-DTCS (DTCS-P475S) and the enzymatic parameters of MDTCS-P475S. Structural analysis showed that the conformation of the V-loop was significantly different in DTCS-P475S, where no obvious interactions of Ser475 with other residues were observed. MDTCS-P475S showed a reaction rate similar to that of wild-type MDTCS, but showed two-fold lower affinity for the peptidyl substrate. MDTCS-P475S can moderately cleave shear-treated VWF. We have provided structural evidence that the P475S polymorphism in ADAMTS-13 leads to increased local structural instability, resulting in lowered affinity for the substrate without changing the reaction rate. The moderate activity of ADAMTS-13-P475S for shear-treated VWF is sufficient to prevent thrombotic thrombocytopenic purpura onset.