title: Mitochondrial cytochrome c1 is a collapsed di-heme cytochrome.
abstract: Cytochrome c(1) from mitochondrial complex III and the di-heme cytochromes c in the corresponding enzyme from epsilon-proteobacteria have so far been considered to represent unrelated cytochromes. A missing link protein discovered in the genome of the hyperthermophilic bacterium Aquifex aeolicus, however, provides evidence for a close evolutionary relationship between these two cytochromes. The mono-heme cytochrome c(1) from A. aeolicus contains stretches of strong sequence homology toward the epsilon-proteobacterial di-heme cytochromes. These di-heme cytochromes are shown to belong to the cytochrome c(4) family. Mapping cytochrome c(1) onto the di-heme sequences and structures demonstrates that cytochrome c(1) results from a mutation-induced collapse of the di-heme cytochrome structure and provides an explanation for its uncommon structural features. The appearance of cytochrome c(1) thus represents an extension of the biological protein repertoire quite different from the widespread innovation by gene duplication and subsequent diversification.
authors.affiliation: Bioénergétique et Ingénierie des Protéines/Institut de Biologie Structurale et Microbiologie, Centre National de la Recherche Scientifique, Marseille, 31, Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France. baymann@ibsm.cnrs-mrs.fr
authors.forename: Frauke
authors.initials: F
authors.lastname: Baymann
authors.forename: Evelyne
authors.initials: E
authors.lastname: Lebrun
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Nitschke
mesh_terms: D000595:Amino Acid Sequence; D003574:Cytochrome c Group / Q000737:chemistry / Q000235:genetics; D003575:Cytochromes c1 / Q000737:chemistry* / Q000145:classification* / Q000235:genetics; D019143:Evolution, Molecular; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000145:classification* / Q000235:genetics; D010802:Phylogeny; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry; D016415:Sequence Alignment; D013997:Time Factors
chemical_list: D003574:Cytochrome c Group; D021122:Protein Subunits; C034186:cytochrome C4; D003575:Cytochromes c1; D010088:Oxidoreductases; C090099:diheme cytochrome c