Structural Basis and Kinetics of DsbD-Dependent Cytochrome c Maturation

• DOI: 10.1016/j.str.2005.04.014
• Publication Date: 2005-07-13T19:42:51Z
• Authors: Christian U. Stir...; Anna Rozhkova; Ulla Grauschopf; Markus G. Grütter; Rudi Glockshuber; Guido Capitani
• Keywords: Models, Molecular; Cytoplasm; Protein Conformation; Electrons; Crystallography, X-Ray; Models, Biological; Electron Transport; 03 medical and health sciences; Structural Biology; Escherichia coli; Disulfides; Molecular Biology; Chromatography, High Pressure Liquid; 0303 health sciences; Binding Sites; Escherichia coli Proteins; Cytochromes c; Membrane Proteins; 3. Good health; Oxygen; Kinetics; Oxidoreductases; Dimerization; Oxidation-Reduction; Plasmids

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 x 10(5) M(-1)s(-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 A 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.