title: A four-subunit cytochrome bc(1) complex complements the respiratory chain of Thermus thermophilus.
abstract: Several components of the respiratory chain of the eubacterium Thermus thermophilus have previously been characterized to various extent, while no conclusive evidence for a cytochrome bc(1) complex has been obtained. Here, we show that four consecutive genes encoding cytochrome bc(1) subunits are organized in an operon-like structure termed fbcCXFB. The four gene products are identified as genuine subunits of a cytochrome bc(1) complex isolated from membranes of T. thermophilus. While both the cytochrome b and the FeS subunit show typical features of canonical subunits of this respiratory complex, a further membrane-integral component (FbcX) of so far unknown function copurifies as a subunit of this complex. The cytochrome c(1) carries an extensive N-terminal hydrophilic domain, followed by a hydrophobic, presumably membrane-embedded helical region and a typical heme c binding domain. This latter sequence has been expressed in Escherichia coli, and in vitro shown to be a kinetically competent electron donor to cytochrome c(552), mediating electron transfer to the ba(3) oxidase. Identification of this cytochrome bc(1) complex bridges the gap between the previously reported NADH oxidation activities and terminal oxidases, thus, defining all components of a minimal, mitochondrial-type electron transfer chain in this evolutionary ancient thermophile.
authors.affiliation: Molekulare Genetik, Institut für Biochemie, Biozentrum der J. W. Goethe-Universität, Marie-Curie-Strasse 9, D-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: Carsten
authors.initials: C
authors.lastname: Corvey
authors.forename: Thomas
authors.initials: T
authors.lastname: Steiner
authors.forename: Francesco
authors.initials: F
authors.lastname: Malatesta
authors.forename: Michael
authors.initials: M
authors.lastname: Karas
authors.forename: Tewfik
authors.initials: T
authors.lastname: Soulimane
authors.forename: Bernd
authors.initials: B
authors.lastname: Ludwig
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004579:Electron Transport; D014450:Electron Transport Complex III / Q000737:chemistry / Q000378:metabolism*; D047468:Immunoprecipitation; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D016963:Thermus thermophilus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D017931:DNA Primers; D014450:Electron Transport Complex III