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Stabilization of warfarin‐binding pocket of VKORC 1 and VKORL 1 by a peripheral region determines their different sensitivity to warfarin inhibition
Author(s) -
Shen G.,
Li S.,
Cui W.,
Liu S.,
Liu Q.,
Yang Y.,
Gross M.,
Li W.
Publication year - 2018
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.14127
Subject(s) - vitamin k epoxide reductase , vkorc1 , warfarin , biology , genetics , medicine , gene , atrial fibrillation , genotype , pharmacogenetics
SummaryEssentials VKORL1 and VKORC1 have a similar overall structure and warfarin‐binding pocket. A peripheral region stabilizing this pocket controls warfarin sensitivity of the VKOR paralogs. A human single nucleotide polymorphism in this region renders VKORL1 sensitive to warfarin. A group of warfarin‐resistant mutations in VKORC1 acts by disrupting peripheral interactions.Summary Background The human genome encodes two paralogs of vitamin‐K‐epoxide reductase, VKORC 1 and VKORL 1, that support blood coagulation and other vitamin‐K‐dependent processes. Warfarin inhibits both enzymes, but VKORL 1 is relatively resistant to warfarin. Objectives To understand the difference between VKORL 1 and VKORC 1, and the cause of warfarin‐resistant ( WR ) mutations in VKORC 1. Methods We performed systematic mutagenesis and analyzed warfarin responses with a cell‐based activity assay. Mass spectrometry analyses were used to detect cellular redox state. Results VKORC 1 and VKORL 1 adopt a similar intracellular redox state with four‐transmembrane‐helix topology. Most WR mutations identified in VKORC 1 also confer resistance in VKORL 1, indicating that warfarin inhibits these paralogs at a common binding site. A group of WR mutations, distant from the warfarin‐binding site, show significantly less resistance in VKORL 1 than in VKORC 1, implying that their different warfarin responses are determined by peripheral interactions. Remarkably, we identify a critical peripheral region in which single mutations, Glu37Lys or His46Tyr, drastically increase the warfarin sensitivity of VKORL 1. In the background of these warfarin‐sensitive VKORL 1 mutants, WR mutations showing relative less resistance in wild‐type VKORL 1 become much more resistant, suggesting a structural conversion to resemble VKORC 1. At this peripheral region, we also identified a human single nucleotide polymorphism that confers warfarin sensitivity of VKORL 1. Conclusions Peripheral regions of VKORC 1 and VKORL 1 primarily maintain the stability of their common warfarin‐binding pocket, and differences of such interactions determine their relative sensitivity to warfarin inhibition. This new model also explains most WR mutations located at the peripheral regions of VKORC 1.