title: Composition of complex I from Neurospora crassa and disruption of two "accessory" subunits.
abstract: Respiratory chain complex I of the fungus Neurospora crassa contains at least 39 polypeptide subunits, of which 35 are conserved in mammals. The 11.5 kDa and 14 kDa proteins, homologues of bovine IP15 and B16.6, respectively, are conserved among eukaryotes and belong to the membrane domain of the fungal enzyme. The corresponding genes were separately inactivated by repeat-induced point-mutations, and null-mutant strains of the fungus were isolated. The lack of either subunit leads to the accumulation of distinct intermediates of the membrane arm of complex I. In addition, the peripheral arm of the enzyme seems to be formed in mutant nuo14 but, interestingly, not in mutant nuo11.5. These results and the analysis of enzymatic activities of mutant mitochondria indicate that both polypeptides are required for complex I assembly and function.
authors.affiliation: Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Marques
authors.forename: Margarida
authors.initials: M
authors.lastname: Duarte
authors.forename: Joana
authors.initials: J
authors.lastname: Assunção
authors.forename: Alexandra V
authors.initials: AV
authors.lastname: Ushakova
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Videira
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D003001:Cloning, Molecular; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000235:genetics; D024101:Mitochondrial Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D009492:Neurospora crassa / Q000201:enzymology*; D010100:Oxygen / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000235:genetics
chemical_list: D024101:Mitochondrial Proteins; D021122:Protein Subunits; D042967:Electron Transport Complex I; D010100:Oxygen