Crystal structure of the protein disulfide bond isomerase, DsbC, from Escherichia coli

DsbC is one of five Escherichia coli proteins required for disulfide bond f ormation and is thought to function as a disulfide bond isomerase during ox idative protein folding in the periplasm. DsbC is a 2 x 23 kDa homodimer an d has both protein disulfide isomerase and chaperone activity. We report th e 1.9 Angstrom resolution crystal structure of oxidized DsbC where both Cys -X-X-Cys active sites form disulfide bonds. The molecule consists of separa te thioredoxin-like domains joined via hinged linker helices to an N-termin al dimerization domain. The hinges allow relative movement of the active si tes, and a broad uncharged deft between them may be involved in peptide bin ding and DsbC foldase activities.