title: A directional electron transfer regulator based on heme-chain architecture in the small tetraheme cytochrome c from Shewanella oneidensis.
abstract: The macroscopic and microscopic redox potentials of the four hemes of the small tetraheme cytochrome c from Shewanella oneidensis were determined. The microscopic redox potentials show that the order of reduction is from hemes in the C-terminal domain (hemes 3 and 4) to the N-terminal domain (heme 1), demonstrating the polarization of the tetraheme chain during reduction. This makes heme 4 the most efficient electron delivery site. Furthermore, multi-step reduction of other redox centers through either heme 4 or heme 3 is shown to be possible. This has provided new insights into the two-electron reduction of the flavin in the homologous flavocytochrome c-fumarate reductase.
authors.affiliation: Institute for Protein Research, Osaka University, Yamadaoka, Suita, 565-0871, Osaka, Japan.
authors.forename: Erisa
authors.initials: E
authors.lastname: Harada
authors.forename: Jiro
authors.initials: J
authors.lastname: Kumagai
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ozawa
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Imabayashi
authors.forename: Alexandre S
authors.initials: AS
authors.lastname: Tsapin
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Nealson
authors.forename: Terrance E
authors.initials: TE
authors.lastname: Meyer
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cusanovich
authors.forename: Hideo
authors.initials: H
authors.lastname: Akutsu
mesh_terms: D001665:Binding Sites; D003574:Cytochrome c Group / Q000378:metabolism*; D004583:Electrons; D006418:Heme / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020592:Shewanella / Q000201:enzymology / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D003574:Cytochrome c Group; D006418:Heme; D011189:Potassium Chloride; D010088:Oxidoreductases; D013385:Succinate Dehydrogenase; C064500:flavocytochrome c sulfide dehydrogenase