Characterization of DorC from Rhodobacter capsulatus, a c-type cytochrome involved in electron transfer to dimethyl sulfoxide reductase.
The dorC gene of the dimethyl sulfoxide respiratory (dor) operon of Rhodobacter capsulatus encodes a pentaheme c-type cytochrome that is involved in electron transfer from ubiquinol to periplasmic dimethyl sulfoxide reductase. DorC was expressed as a C-terminal fusion to an 8-amino acid FLAG epitope and was purified from detergent-solubilized membranes by ion exchange chromatography and immunoaffinity chromatography. The DorC protein had a subunit Mr = 46,000, and pyridine hemochrome analysis indicated that it contained 5 mol heme c/mol DorC polypeptide, as predicted from the derived amino acid sequence of the dorC gene. The reduced form of DorC exhibited visible absorption maxima at 551.5 nm (alpha-band), 522 nm (beta-band), and 419 nm (Soret band). Redox potentiometry of the heme centers of DorC identified five components (n = 1) with midpoint potentials of -34, -128, -184, -185, and -276 mV. Despite the low redox potentials of the heme centers, DorC was reduced by duroquinol and was oxidized by dimethyl sulfoxide reductase.
Shaw
A L
AL
Department of Microbiology, The University of Queensland, Brisbane 4072, Australia.
Hochkoeppler
A
A
Bonora
P
P
Zannoni
D
D
Hanson
G R
GR
McEwan
A G
AG
D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism; D004227:Dithionite; D004579:Electron Transport; D004591:Electrophoresis, Polyacrylamide Gel; D005292:Ferricyanides / Q000378:metabolism; D007506:Iron-Sulfur Proteins; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D011199:Potentiometry; D016354:Rhodobacter capsulatus / Q000201:enzymology / Q000235:genetics*
D003574:Cytochrome c Group; D005292:Ferricyanides; D007506:Iron-Sulfur Proteins; C007931:hexacyanoferrate III; D004227:Dithionite; D010088:Oxidoreductases; C045664:dimethyl sulfoxide reductase