title: The disulfide bond isomerase DsbC is activated by an immunoglobulin-fold thiol oxidoreductase: crystal structure of the DsbC-DsbDalpha complex.
abstract: The Escherichia coli disulfide bond isomerase DsbC rearranges incorrect disulfide bonds during oxidative protein folding. It is specifically activated by the periplasmic N-terminal domain (DsbDalpha) of the transmembrane electron transporter DsbD. An intermediate of the electron transport reaction was trapped, yielding a covalent DsbC-DsbDalpha complex. The 2.3 A crystal structure of the complex shows for the first time the specific interactions between two thiol oxidoreductases. DsbDalpha is a novel thiol oxidoreductase with the active site cysteines embedded in an immunoglobulin fold. It binds into the central cleft of the V-shaped DsbC dimer, which assumes a closed conformation on complex formation. Comparison of the complex with oxidized DsbDalpha reveals major conformational changes in a cap structure that regulates the accessibility of the DsbDalpha active site. Our results explain how DsbC is selectively activated by DsbD using electrons derived from the cytoplasm.
authors.affiliation: School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealandand.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Haebel
authors.forename: David
authors.initials: D
authors.lastname: Goldstone
authors.forename: Federico
authors.initials: F
authors.lastname: Katzen
authors.forename: Jon
authors.initials: J
authors.lastname: Beckwith
authors.forename: Peter
authors.initials: P
authors.lastname: Metcalf
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D010084:Oxidation-Reduction; D019704:Protein Disulfide-Isomerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D004220:Disulfides; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D019704:Protein Disulfide-Isomerases