title: Truncation of subunit ND2 disrupts the threefold symmetry of the antiporter-like subunits in complex I from higher metazoans.
abstract: Three of the conserved, membrane-bound subunits in NADH:ubiquinone oxidoreductase (complex I) are related to one another, and to Mrp sodium-proton antiporters. Recent structural analysis of two prokaryotic complexes I revealed that the three subunits each contain fourteen transmembrane helices that overlay in structural alignments: the translocation of three protons may be coordinated by a lateral helix connecting them together (Efremov, R.G., Baradaran, R. and Sazanov, L.A. (2010). The architecture of respiratory complex I. Nature 465, 441-447). Here, we show that in higher metazoans the threefold symmetry is broken by the loss of three helices from subunit ND2; possible implications for the mechanism of proton translocation are discussed.
authors.affiliation: Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Cambridge, UK.
authors.forename: James A
authors.initials: JA
authors.lastname: Birrell
authors.forename: Judy
authors.initials: J
authors.lastname: Hirst
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D017173:Caenorhabditis elegans / Q000201:enzymology / Q000235:genetics; D002417:Cattle; D044723:Chondrus / Q000201:enzymology / Q000235:genetics; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D017386:Sequence Homology, Amino Acid; D016963:Thermus thermophilus / Q000201:enzymology / Q000235:genetics; D025062:Yarrowia / Q000201:enzymology / Q000235:genetics
chemical_list: D021122:Protein Subunits; D042967:Electron Transport Complex I