title: The Rieske/cytochrome b complex of Heliobacteria.
abstract: Heliobacteria have a Rieske/cytochrome b complex composed of a Rieske protein, a cytochrome b(6,) a subunit IV and a di-heme cytochrome c. The overall structure of the complex seems close to the b(6)f complex from cyanobacteria and chloroplasts to the exception of the di-heme cytochrome. We show here by biochemical and biophysical studies that a heme c(i) is covalently attached to the Rieske/cytochrome b complex from Heliobacteria. We studied the EPR signature of this heme in two different species, Heliobacterium modesticaldum and Heliobacillus mobilis. In contrast to the case of b(6)f complex, a strong axial ligand to the heme is present, most probably a protonatable amino acid residue.
authors.affiliation: Laboratoire de Bioénergétique et Ingénierie des protéines, Institut de Biologie Structurale et Microbiologie, Unité Propre de Recherche 9036, Centre National de la Recherche Scientifique, 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
authors.forename: A L
authors.initials: AL
authors.lastname: Ducluzeau
authors.forename: E
authors.initials: E
authors.lastname: Chenu
authors.forename: L
authors.initials: L
authors.lastname: Capowiez
authors.forename: F
authors.initials: F
authors.lastname: Baymann
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D045303:Cytochromes b / Q000737:chemistry / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D014450:Electron Transport Complex III / Q000737:chemistry / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006094:Gram-Positive Bacteria / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006418:Heme / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006912:Hydroxyquinolines / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016415:Sequence Alignment
chemical_list: D006912:Hydroxyquinolines; C037989:Rieske iron-sulfur protein; C010494:nonyl-4-hydroxyquinoline-N-oxide; D006418:Heme; D045303:Cytochromes b; D014450:Electron Transport Complex III