title: Structural organization of mitochondrial human complex I: role of the ND4 and ND5 mitochondria-encoded subunits and interaction with prohibitin.
abstract: Mitochondria-encoded ND (NADH dehydrogenase) subunits, as components of the hydrophobic part of complex I, are essential for NADH:ubiquinone oxidoreductase activity. Mutations or lack of expression of these subunits have significant pathogenic consequences in humans. However, the way these events affect complex I assembly is poorly documented. To understand the effects of particular mutations in ND subunits on complex I assembly, we studied four human cell lines: ND4 non-expressing cells, ND5 non-expressing cells, and rho degrees cells that do not express any ND subunits, in comparison with normal complex I control cells. In control cells, all the seven analysed nuclear-encoded complex I subunits were found to be attached to the mitochondrial inner membrane, except for the 24 kDa subunit, which was nearly equally partitioned between the membranes and the matrix. Absence of a single ND subunit, or even all the seven ND subunits, caused no major changes in the nuclear-encoded complex I subunit content of mitochondria. However, in cells lacking ND4 or ND5, very low amounts of 24 kDa subunit were found associated with the membranes, whereas most of the other nuclear-encoded subunits remained attached. In contrast, membrane association of most of the nuclear subunits was significantly reduced in the absence of all seven ND proteins. Immunopurification detected several subcomplexes. One of these, containing the 23, 30 and 49 kDa subunits, also contained prohibitin. This is the first description of prohibitin interaction with complex I subunits and suggests that this protein might play a role in the assembly or degradation of mitochondrial complex I.
authors.affiliation: UMR 5090 CNRS-DRDC, CEA Grenoble, 38054 Grenoble cedex 9, France.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Bourges
authors.forename: Claire
authors.initials: C
authors.lastname: Ramus
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Mousson de Camaret
authors.forename: Réjane
authors.initials: R
authors.lastname: Beugnot
authors.forename: Claire
authors.initials: C
authors.lastname: Remacle
authors.forename: Pierre
authors.initials: P
authors.lastname: Cardol
authors.forename: Götz
authors.initials: G
authors.lastname: Hofhaus
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Issartel
mesh_terms: D001859:Bone Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid / Q000379:methods; D004273:DNA, Neoplasm / Q000235:genetics; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology*; D005838:Genotype; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008928:Mitochondria / Q000201:enzymology* / Q000502:physiology; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000502:physiology; D009245:NADH Dehydrogenase / Q000737:chemistry / Q000502:physiology*; D012516:Osteosarcoma / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D010085:Oxidative Phosphorylation; D000091402:Prohibitins; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D012097:Repressor Proteins / Q000378:metabolism*
chemical_list: D004273:DNA, Neoplasm; D024101:Mitochondrial Proteins; C098483:NADH dehydrogenase subunit 4; D000091402:Prohibitins; D021122:Protein Subunits; D012097:Repressor Proteins; C481838:MT-ND5 protein, human; D009245:NADH Dehydrogenase; D042967:Electron Transport Complex I