title: Structure and function of complex I in animals and plants - a comparative view.
abstract: The mitochondrial NADH dehydrogenase complex (complex I) has a molecular mass of about 1000 kDa and includes 40-50 subunits in animals, fungi and plants. It is composed of a membrane arm and a peripheral arm and has a conserved L-like shape in all species investigated. However, in plants and possibly some protists it has a second peripheral domain which is attached to the membrane arm on its matrix exposed side at a central position. The extra domain includes proteins resembling prokaryotic gamma-type carbonic anhydrases. We here present a detailed comparison of complex I from mammals and flowering plants. Forty homologous subunits are present in complex I of both groups of species. In addition, five subunits are present in mammalian complex I, which are absent in plants, and eight to nine subunits are present in plant complex I which do not occur in mammals. Based on the atomic structure of mammalian complex I and biochemical insights into complex I architecture from plants we mapped the species-specific subunits. Interestingly, four of the five animal-specific and five of the eight to nine plant-specific subunits are localized at the inner surface of the membrane arm of complex I in close proximity. We propose that the inner surface of the membrane arm represents a workbench for attaching proteins to complex I, which are not directly related to respiratory electron transport, like nucleoside kinases, acyl-carrier proteins or carbonic anhydrases. We speculate that further enzyme activities might be bound to this micro-location in other groups of organisms.
authors.affiliation: Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Senkler
authors.affiliation: Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Senkler
authors.affiliation: Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany.
authors.forename: Hans-Peter
authors.identifier: http://orcid.org/0000-0002-4459-9727
authors.initials: HP
authors.lastname: Braun
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D008958:Models, Molecular; D010944:Plants / Q000378:metabolism*
chemical_list: D042967:Electron Transport Complex I