title: Human mitochondrial complex I assembly is mediated by NDUFAF1.
abstract: Complex I (NADH:ubiquinone oxidoreductase) is the largest multiprotein enzyme of the oxidative phosphorylation system. Its assembly in human cells is poorly understood and no proteins assisting this process have yet been described. A good candidate is NDUFAF1, the human homologue of Neurospora crassa complex I chaperone CIA30. Here, we demonstrate that NDUFAF1 is a mitochondrial protein that is involved in the complex I assembly process. Modulating the intramitochondrial amount of NDUFAF1 by knocking down its expression using RNA interference leads to a reduced amount and activity of complex I. NDUFAF1 is associated to two complexes of 600 and 700 kDa in size of which the relative distribution is altered in two complex I deficient patients. Analysis of NDUFAF1 expression in a conditional complex I assembly system shows that the 700 kDa complex may represent a key step in the complex I assembly process. Based on these data, we propose that NDUFAF1 is an important protein for the assembly/stability of complex I.
authors.affiliation: Department of Paediatrics, Radboud University Nijmegen Medical Centre, Netherlands.
authors.forename: Rutger O
authors.initials: RO
authors.lastname: Vogel
authors.forename: Rolf J R J
authors.initials: RJ
authors.lastname: Janssen
authors.forename: Cristina
authors.initials: C
authors.lastname: Ugalde
authors.forename: Melissa
authors.initials: M
authors.lastname: Grovenstein
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Huijbens
authors.forename: Henk-Jan
authors.initials: HJ
authors.lastname: Visch
authors.forename: Lambert P
authors.initials: LP
authors.lastname: van den Heuvel
authors.forename: Peter H
authors.initials: PH
authors.lastname: Willems
authors.forename: Massimo
authors.initials: M
authors.lastname: Zeviani
authors.forename: Jan A M
authors.initials: JA
authors.lastname: Smeitink
authors.forename: Leo G J
authors.initials: LG
authors.lastname: Nijtmans
mesh_terms: D002458:Cell Fractionation; D002460:Cell Line; D004318:Doxycycline / Q000494:pharmacology; D042967:Electron Transport Complex I / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D028361:Mitochondrial Diseases / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D009154:Mutation / Q000235:genetics; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics; D009245:NADH Dehydrogenase; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection
chemical_list: D008565:Membrane Proteins; D024101:Mitochondrial Proteins; C113982:NDUFS8 protein, human; D021122:Protein Subunits; D034741:RNA, Small Interfering; D016660:NAD(P)H Dehydrogenase (Quinone); C481838:MT-ND5 protein, human; D009245:NADH Dehydrogenase; C117108:cytochrome C oxidase subunit II; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I; C506342:NDUFAF1 protein, human; D004318:Doxycycline