title: The obligate respiratory supercomplex from Actinobacteria.
abstract: Actinobacteria are closely linked to human life as industrial producers of bioactive molecules and as human pathogens. Respiratory cytochrome bcc complex and cytochrome aa3 oxidase are key components of their aerobic energy metabolism. They form a supercomplex in the actinobacterial species Corynebacterium glutamicum. With comprehensive bioinformatics and phylogenetic analysis we show that genes for cyt bcc-aa3 supercomplex are characteristic for Actinobacteria (Actinobacteria and Acidimicrobiia, except the anaerobic orders Actinomycetales and Bifidobacteriales). An obligatory supercomplex is likely, due to the lack of genes encoding alternative electron transfer partners such as mono-heme cyt c. Instead, subunit QcrC of bcc complex, here classified as short di-heme cyt c, will provide the exclusive electron transfer link between the complexes as in C. glutamicum. Purified to high homogeneity, the C. glutamicum bcc-aa3 supercomplex contained all subunits and cofactors as analyzed by SDS-PAGE, BN-PAGE, absorption and EPR spectroscopy. Highly uniform supercomplex particles in electron microscopy analysis support a distinct structural composition. The supercomplex possesses a dimeric stoichiometry with a ratio of a-type, b-type and c-type hemes close to 1:1:1. Redox titrations revealed a low potential bcc complex (Em(ISP)=+160mV, Em(bL)=-291mV, Em(bH)=-163mV, Em(cc)=+100mV) fined-tuned for oxidation of menaquinol and a mixed potential aa3 oxidase (Em(CuA)=+150mV, Em(a/a3)=+143/+317mV) mediating between low and high redox potential to accomplish dioxygen reduction. The generated molecular model supports a stable assembled supercomplex with defined architecture which permits energetically efficient coupling of menaquinol oxidation and dioxygen reduction in one supramolecular entity.
authors.affiliation: Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, BIOSS Centre for Biological Signalling Studies, 79104 Freiburg, Germany.
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Kao
authors.affiliation: Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, BIOSS Centre for Biological Signalling Studies, 79104 Freiburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kleinschroth
authors.affiliation: Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/Aix Marseille Univ, FR3479, 13009 Marseille, France.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Nitschke
authors.affiliation: Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/Aix Marseille Univ, FR3479, 13009 Marseille, France.
authors.forename: Frauke
authors.initials: F
authors.lastname: Baymann
authors.affiliation: Laboratoire de bioélectrochimie et spectroscopie, UMR 7140, Chimie de la matière complexe, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France.
authors.forename: Yashvin
authors.initials: Y
authors.lastname: Neehaul
authors.affiliation: Laboratoire de bioélectrochimie et spectroscopie, UMR 7140, Chimie de la matière complexe, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France.
authors.forename: Petra
authors.initials: P
authors.lastname: Hellwig
authors.affiliation: Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Richers
authors.affiliation: Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany.
authors.forename: Janet
authors.initials: J
authors.lastname: Vonck
authors.affiliation: Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52428 Jülich, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bott
authors.affiliation: Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, BIOSS Centre for Biological Signalling Studies, 79104 Freiburg, Germany. Electronic address: carola.hunte@biochemie.uni-freiburg.de.
authors.forename: Carola
authors.initials: C
authors.lastname: Hunte
mesh_terms: D039903:Actinobacteria / Q000378:metabolism* / Q000502:physiology*; D019069:Cell Respiration / Q000502:physiology*; D003352:Corynebacterium / Q000378:metabolism / Q000502:physiology; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004579:Electron Transport / Q000502:physiology; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006418:Heme / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010802:Phylogeny
chemical_list: C031690:heme C; D006418:Heme; D010088:Oxidoreductases; D003576:Electron Transport Complex IV; D010100:Oxygen
keywords: Actinobacteria; cytochrome bc(1) complex; cytochrome oxidase; menaquinone; respiratory chain; supercomplex