title: nde1 deletion improves mitochondrial DNA maintenance in Saccharomyces cerevisiae coenzyme Q mutants.
abstract: Saccharomyces cerevisiae has three distinct inner mitochondrial membrane NADH dehydrogenases mediating the transfer of electrons from NADH to CoQ (coenzyme Q): Nde1p, Nde2p and Ndi1p. The active site of Ndi1p faces the matrix side, whereas the enzymatic activities of Nde1p and Nde2p are restricted to the intermembrane space side, where they are responsible for cytosolic NADH oxidation. In the present study we genetically manipulated yeast strains in order to alter the redox state of CoQ and NADH dehydrogenases to evaluate the consequences on mtDNA (mitochondrial DNA) maintenance. Interestingly, nde1 deletion was protective for mtDNA in strains defective in CoQ function. Additionally, the absence of functional Nde1p promoted a decrease in the rate of H2O2 release in isolated mitochondria from different yeast strains. On the other hand, overexpression of the predominant NADH dehydrogenase NDE1 elevated the rate of mtDNA loss and was toxic to coq10 and coq4 mutants. Increased CoQ synthesis through COQ8 overexpression also demonstrated that there is a correlation between CoQ respiratory function and mtDNA loss: supraphysiological CoQ levels were protective against mtDNA loss in the presence of oxidative imbalance generated by Nde1p excess or exogenous H2O2. Altogether, our results indicate that impairment in the oxidation of cytosolic NADH by Nde1p is deleterious towards mitochondrial biogenesis due to an increase in reactive oxygen species release.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, 05508-900 São Paulo, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Gomes
authors.forename: Erich B
authors.initials: EB
authors.lastname: Tahara
authors.forename: Cleverson
authors.initials: C
authors.lastname: Busso
authors.forename: Alicia J
authors.initials: AJ
authors.lastname: Kowaltowski
authors.forename: Mario H
authors.initials: MH
authors.lastname: Barros
mesh_terms: D001483:Base Sequence; D004271:DNA, Fungal / Q000235:genetics* / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000235:genetics* / Q000378:metabolism*; D042967:Electron Transport Complex I / Q000235:genetics* / Q000378:metabolism*; D014450:Electron Transport Complex III / Q000235:genetics / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D006861:Hydrogen Peroxide / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D009243:NAD / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D014451:Ubiquinone / Q000235:genetics* / Q000378:metabolism*
chemical_list: C433869:COQ4 protein, S cerevisiae; C554561:Coq10 protein, S cerevisiae; D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; D029701:Saccharomyces cerevisiae Proteins; D009243:NAD; D014451:Ubiquinone; D006861:Hydrogen Peroxide; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III