title: The acidic domain of cytochrome c₁ in paracoccus denitrificans, analogous to the acidic subunits in eukaryotic bc₁ complexes, is not involved in the electron transfer reaction to its native substrate cytochrome c(552).
abstract: The cytochrome bc(1) complex is a key component in several respiratory pathways. One of the characteristics of the eukaryotic complex is the presence of a small acidic subunit, which is thought to guide the interaction of the complex with its electron acceptor and facilitate electron transfer. Paracoccus denitrificans represents the only example of a prokaryotic organism in which a highly acidic domain is covalently fused to the cytochrome c(1) subunit. In this work, a deletion variant lacking this acidic domain has been produced and purified by affinity chromatography. The complex is fully intact as shown by its X-ray structure, and is a dimer (Kleinschroth et al., subm.) compared to the tetrameric (dimer-of-dimer) state of the wild-type. The variant complex is studied by steady-state kinetics and flash photolysis, showing wild type turnover and a virtually identical interaction with its substrate cytochrome c(552).
authors.affiliation: Institute of Biochemistry, Molecular Genetics, Goethe University, D-60438 Frankfurt am Main and Cluster of Excellence "Macromolecular Complexes" (CEF-MC), D-60438 Frankfurt am Main, Germany.
authors.forename: Michela
authors.initials: M
authors.lastname: Castellani
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Havens
authors.forename: Thomas
authors.initials: T
authors.lastname: Kleinschroth
authors.forename: Francis
authors.initials: F
authors.lastname: Millett
authors.forename: Bill
authors.initials: B
authors.lastname: Durham
authors.forename: Francesco
authors.initials: F
authors.lastname: Malatesta
authors.forename: Bernd
authors.initials: B
authors.lastname: Ludwig
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism*; D003575:Cytochromes c1 / Q000737:chemistry* / Q000378:metabolism; D004579:Electron Transport / Q000502:physiology*; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010231:Paracoccus denitrificans / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003574:Cytochrome c Group; D021122:Protein Subunits; D003575:Cytochromes c1; C022302:cytochrome C-552; D014450:Electron Transport Complex III