Human mitochondrial complex I assembly is mediated by NDUFAF1.
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.
Vogel
Rutger O
RO
Department of Paediatrics, Radboud University Nijmegen Medical Centre, Netherlands.
Janssen
Rolf J R J
RJ
Ugalde
Cristina
C
Grovenstein
Melissa
M
Huijbens
Richard J
RJ
Visch
Henk-Jan
HJ
van den Heuvel
Lambert P
LP
Willems
Peter H
PH
Zeviani
Massimo
M
Smeitink
Jan A M
JA
Nijtmans
Leo G J
LG
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
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