title: Accessory NUMM (NDUFS6) subunit harbors a Zn-binding site and is essential for biogenesis of mitochondrial complex I.
abstract: Mitochondrial proton-pumping NADH:ubiquinone oxidoreductase (respiratory complex I) comprises more than 40 polypeptides and contains eight canonical FeS clusters. The integration of subunits and insertion of cofactors into the nascent complex is a complicated multistep process that is aided by assembly factors. We show that the accessory NUMM subunit of complex I (human NDUFS6) harbors a Zn-binding site and resolve its position by X-ray crystallography. Chromosomal deletion of the NUMM gene or mutation of Zn-binding residues blocked a late step of complex I assembly. An accumulating assembly intermediate lacked accessory subunit N7BM (NDUFA12), whereas a paralog of this subunit, the assembly factor N7BML (NDUFAF2), was found firmly bound instead. EPR spectroscopic analysis and metal content determination after chromatographic purification of the assembly intermediate showed that NUMM is required for insertion or stabilization of FeS cluster N4.
authors.affiliation: Structural Bioenergetics Group, Institute of Biochemistry II, Medical School, Goethe University, 60438 Frankfurt am Main, Germany;
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kmita
authors.affiliation: Institute for Biochemistry and Molecular Biology, ZBMZ, BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg Germany;
authors.forename: Christophe
authors.initials: C
authors.lastname: Wirth
authors.affiliation: Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany;
authors.forename: Judith
authors.initials: J
authors.lastname: Warnau
authors.affiliation: Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; Cluster of Excellence Frankfurt "Macromolecular Complexes", Goethe University, 60438 Frankfurt am Main, Germany;
authors.forename: Sergio
authors.initials: S
authors.lastname: Guerrero-Castillo
authors.affiliation: Institute for Biochemistry and Molecular Biology, ZBMZ, BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg Germany;
authors.forename: Carola
authors.initials: C
authors.lastname: Hunte
authors.affiliation: Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany;
authors.forename: Gerhard
authors.initials: G
authors.lastname: Hummer
authors.affiliation: Department Chemie, Technische Universität München, 85747 Garching, Germany; and.
authors.forename: Ville R I
authors.initials: VR
authors.lastname: Kaila
authors.affiliation: Institute of Biochemistry I, Medical School, Goethe University, 60590 Frankfurt am Main, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Zwicker
authors.affiliation: Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; Cluster of Excellence Frankfurt "Macromolecular Complexes", Goethe University, 60438 Frankfurt am Main, Germany;
authors.forename: Ulrich
authors.initials: U
authors.lastname: Brandt
authors.affiliation: Structural Bioenergetics Group, Institute of Biochemistry II, Medical School, Goethe University, 60438 Frankfurt am Main, Germany; Cluster of Excellence Frankfurt "Macromolecular Complexes", Goethe University, 60438 Frankfurt am Main, Germany; zickermann@med.uni-frankfurt.de.
authors.forename: Volker
authors.initials: V
authors.lastname: Zickermann
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D042967:Electron Transport Complex I / Q000378:metabolism; D004586:Electrophoresis; D017353:Gene Deletion; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry; D008968:Molecular Conformation; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009245:NADH Dehydrogenase / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D040901:Proteomics; D013053:Spectrophotometry; D015032:Zinc / Q000737:chemistry*
chemical_list: D018832:Molecular Chaperones; D009245:NADH Dehydrogenase; C493878:NDUFS6 protein, human; D042967:Electron Transport Complex I; D015032:Zinc
keywords: FeS cluster; NDUFA12; NDUFAF2; assembly; metal protein