Structure of a bacterial homologue of vitamin K epoxide reductase.

ABSTRACT: Vitamin K epoxide reductase (VKOR) generates vitamin K hydroquinone to sustain gamma-carboxylation of many blood coagulation factors. Here, we report the 3.6 A crystal structure of a bacterial homologue of VKOR from Synechococcus sp. The structure shows VKOR in complex with its naturally fused redox partner, a thioredoxin-like domain, and corresponds to an arrested state of electron transfer. The catalytic core of VKOR is a four transmembrane helix bundle that surrounds a quinone, connected through an additional transmembrane segment with the periplasmic thioredoxin-like domain. We propose a pathway for how VKOR uses electrons from cysteines of newly synthesized proteins to reduce a quinone, a mechanism confirmed by in vitro reconstitution of vitamin K-dependent disulphide bridge formation

SUBMITTER: Li W 

PROVIDER: S-EPMC2919313 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature