title: Synthesis of cytochrome c oxidase subunit 1 is translationally downregulated in the absence of functional F1F0-ATP synthase.
abstract: The mitochondrial F(1)F(0)-ATP synthase or ATPase is a key enzyme for aerobic energy production in eukaryotic cells. Mutations in ATPase structural and assembly genes are the primary cause of severe human encephalomyopathies, frequently associated with a pleiotropic decrease in cytochrome c oxidase (COX) activity. We have studied the structural and functional constraints underlying the COX defect using Saccharomyces cerevisiae genetic and pharmacological models of ATPase deficiency. In both yeast Deltaatp10 and oligomycin-treated wild type cells, COX assembly is selectively impaired in the absence of functional ATPase. The COX biogenesis defect does not involve a primary alteration in the expression of the COX subunits as previously suggested but in their maturation and/or assembly. Expression of COX subunit 1, however, is translationally regulated as in most bona fide COX assembly mutants. Additionally, the COX defect in oligomycin-inhibited ATPase-deficient yeast cells, but not in atp10 cells could be partially prevented by partially dissipating the mitochondrial membrane potential using the uncoupler CCCP. Similar results were obtained with oligomycin-treated and ATP12-deficient human fibroblasts respectively. Our findings imply that fully assembled ATPase and its proton pumping function are both required for COX biogenesis in yeast and mammalian cells through a mechanism independent of Cox1p synthesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine. Miami, FL 33136, USA.
authors.forename: Ileana C
authors.initials: IC
authors.lastname: Soto
authors.forename: Flavia
authors.initials: F
authors.lastname: Fontanesi
authors.forename: Melvys
authors.initials: M
authors.lastname: Valledor
authors.forename: Darryl
authors.initials: D
authors.lastname: Horn
authors.forename: Rajiv
authors.initials: R
authors.lastname: Singh
authors.forename: Antoni
authors.initials: A
authors.lastname: Barrientos
mesh_terms: D000332:Aerobiosis / Q000235:genetics; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D003576:Electron Transport Complex IV; D005347:Fibroblasts / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D017506:H(+)-K(+)-Exchanging ATPase / Q000235:genetics; D006801:Humans; D017237:Mitochondrial Encephalomyopathies / Q000201:enzymology / Q000235:genetics; D008954:Models, Biological; D009154:Mutation; D009840:Oligomycins / Q000494:pharmacology; D006180:Proton-Translocating ATPases; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D009840:Oligomycins; D029701:Saccharomyces cerevisiae Proteins; D014475:Uncoupling Agents; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; C526453:Cox1 protein, S cerevisiae; D003576:Electron Transport Complex IV; D017506:H(+)-K(+)-Exchanging ATPase; D006180:Proton-Translocating ATPases