title: The menaquinol-oxidizing cytochrome bc complex from Thermus thermophilus: protein domains and subunits.
abstract: A recently resolved respiratory complex III, isolated from the extreme thermophile Thermus thermophilus, is discussed in terms of cofactor and subunit composition, and with respect to the origin of its protein modules. The four polypeptides, encoded by a single operon, share general homologies to canonical complexes both of the bc and b6f type, but exhibit some unexpected features as well. Evidence for high thermostability of the isolated protein and for its quinol substrate specificity is derived from EPR and kinetic measurements. A functional integration of this complex into an aerobic electron transfer scheme, connecting known dehydrogenase activities to the terminal oxidase branches of Thermus is outlined, as well as the specific principles of redox protein interactions prevailing at high temperature. Findings from this enzyme are linked to present knowledge on other menaquinol oxidizing bc complexes.
authors.affiliation: Molekulare Genetik, Institut für Biochemie, Biozentrum der J. W. Goethe-Universität, 60439 Frankfurt am Main, Germany. d.mooser@em.uni-frankfurt.de
authors.forename: Daniela
authors.initials: D
authors.lastname: Mooser
authors.forename: Oliver
authors.initials: O
authors.lastname: Maneg
authors.forename: Fraser
authors.initials: F
authors.lastname: MacMillan
authors.forename: Francesco
authors.initials: F
authors.lastname: Malatesta
authors.forename: Tewfik
authors.initials: T
authors.lastname: Soulimane
authors.forename: Bernd
authors.initials: B
authors.lastname: Ludwig
mesh_terms: D000595:Amino Acid Sequence; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016963:Thermus thermophilus / Q000201:enzymology / Q000378:metabolism*; D024482:Vitamin K 2 / Q000378:metabolism*
chemical_list: D021122:Protein Subunits; D024482:Vitamin K 2; D014450:Electron Transport Complex III