Crystal structure analysis for the pathogenesis of thrombosis

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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.