Structural Basis and Kinetics of DsbD-Dependent Cytochrome c Maturation

• Published in: Structure (London) 2005-07, Vol.13 (7), p.985-993
• Main Authors: Stirnimann, Christian U., Rozhkova, Anna, Grauschopf, Ulla, Grütter, Markus G., Glockshuber, Rudi, Capitani, Guido
• Format: Article
• Language: English
• Subjects: Binding Sites; Chromatography, High Pressure Liquid; Crystallography, X-Ray; Cytochromes c - chemistry; Cytoplasm - metabolism; Dimerization; Disulfides - chemistry; Electron Transport; Electrons; Escherichia coli; Escherichia coli - metabolism; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - physiology; Kinetics; Membrane Proteins - chemistry; Membrane Proteins - physiology; Models, Biological; Models, Molecular; Oxidation-Reduction; Oxidoreductases - chemistry; Oxygen - chemistry; Plasmids - metabolism; Protein Conformation; Protein Disulfide Reductase (Glutathione) - chemistry; Protein Structure, Tertiary; Thioredoxins - chemistry; Time Factors
• ISSN: 0969-2126; 1878-4186
• DOI: 10.1016/j.str.2005.04.014

DsbD from Escherichia coli transports two electrons from cytoplasmic thioredoxin to the periplasmic substrate proteins DsbC, DsbG and CcmG. DsbD consists of an N-terminal periplasmic domain (nDsbD), a C-terminal periplasmic domain, and a central transmembrane domain. Each domain possesses two cysteines required for electron transport. Herein, we demonstrate fast (3.9 × 10 5 M −1s −1) and direct disulfide exchange between nDsbD and CcmG, a highly specific disulfide reductase essential for cytochrome c maturation. We determined the crystal structure of the disulfide-linked complex between nDsbD and the soluble part of CcmG at 1.94 Å resolution. In contrast to the other two known complexes of nDsbD with target proteins, the N-terminal segment of nDsbD contributes to specific recognition of CcmG. This and other features, like the possibility of using an additional interaction surface, constitute the structural basis for the adaptability of nDsbD to different protein substrates.