Warfarin analogs target disulfide bond-forming enzymes and suggest a residue important for quinone and coumarin binding

Abstract

Disulfide bond formation has a central role in protein folding of both eukaryotes and prokaryotes. DsbB and VKOR enzymes catalyze the oxidation of the oxidoreductase partner and the formation of de novo disulfide bonds using quinone as cofactor. We have used E. coli and a family of warfarin analogs to study de novo disulfide bond formation. We found that human VKORc1 can function in E. coli by removing two positive residues, allowing the search for novel anticoagulants. One analog was capable of inhibiting both bacterial DsbB and VKOR, and a second one antagonized only the mammalian enzymes. We identified the two amino acid residues responsible for binding. One of these is also essential for quinone binding in both DsbB and VKOR. Our studies highlight a conserved role of this residue in de novo disulfide-generating enzymes and enable the design of novel anticoagulants or antibacterials using coumarin as a scaffold.