Warfarin and vitamin K epoxide reductase: a molecular accounting for observed inhibition

摘要: Vitamin K epoxide reductase (VKOR), an endoplasmic reticulum membrane protein, is the key enzyme for vitamin K-dependent carboxylation, a posttranslational modification that essential biological functions of coagulation factors. VKOR target most widely prescribed oral anticoagulant, warfarin. However, topological structure and mechanism warfarin's inhibition remain elusive. Additionally, it not clear why warfarin-resistant mutations identified in patients significantly decrease binding affinity, but have only minor effect on binding. Here, we used immunofluorescence confocal imaging live mammalian cells PEGylation VKOR's endogenous cytoplasmic-accessible cysteines intact microsomes to probe topology human VKOR. Our results show disputed loop sequence between first second transmembrane (TM) domain located cytoplasm, supporting 3-TM Using molecular dynamics (MD) simulations, T-shaped stacking interaction warfarin tyrosine residue 139, within proposed TY139A warfarin-binding motif, was observed. Furthermore, reversible dynamic pocket opening conformational changes were observed when binds Several residues (Y25, A26, Y139) found by MD these confirmed functional study its mutants their native milieu using cell-based assay. findings provide new insights into VKOR, as well anticoagulation.