Open AccessRestoration of electron transport without proton pumping in mammalian mitochondria
Author(s) -
Ester PeralesClemente,
M. Pilar BayonaBafaluy,
Acisclo PérezMartos,
Antoni Barrientos,
Patricio FernándezSilva,
José Antonio Enrı́quez
Publication year - 2008
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0810518105
Subject(s) - oxidative phosphorylation , mitochondrion , alternative oxidase , electron transport chain , biochemistry , nad+ kinase , reductase , enzyme , atp synthase , oxidase test , dehydrogenase , biology , nadh dehydrogenase , mitochondrial dna , gene
We have restored the CoQ oxidative capacity of mouse mtDNA-less cells (ρ° cells) by transforming them with the alternative oxidaseAox ofEmericella nidulans . Cotransforming ρ° cells with the NADH dehydrogenase ofSaccharomyces cerevisiae ,Ndi1 andAox recovered the NADH DH/CoQ reductase and the CoQ oxidase activities. CoQ oxidation by AOX reduces the dependence of ρ° cells on pyruvate and uridine. Coexpression of AOX and NDI1 further improves the recycling of NAD+ . Therefore, 2 single-protein enzymes restore the electron transport in mammalian mitochondria substituting >80 nuclear DNA-encoded and 11 mtDNA-encoded proteins. Because those enzymes do not pump protons, we were able to split electron transport and proton pumping (ATP synthesis) and inquire which of the metabolic deficiencies associated with the loss of oxidative phosphorylation should be attributed to each of the 2 processes.