Saccharomyces cerevisiae coq10 null mutants are responsive to antimycin A.
Deletion of COQ10 in Saccharomyces cerevisiae elicits a respiratory defect characterized by the absence of cytochrome c reduction, which is correctable by the addition of exogenous diffusible coenzyme Q(2). Unlike other coq mutants with hampered coenzyme Q(6) (Q(6) ) synthesis, coq10 mutants have near wild-type concentrations of Q(6). In the present study, we used Q-cycle inhibitors of the coenzyme QH(2)-cytochrome c reductase complex to assess the electron transfer properties of coq10 cells. Our results show that coq10 mutants respond to antimycin A, indicating an active Q-cycle in these mutants, even though they are unable to transport electrons through cytochrome c and are not responsive to myxothiazol. EPR spectroscopic analysis also suggests that wild-type and coq10 mitochondria accumulate similar amounts of Q(6) semiquinone, despite a lower steady-state level of coenzyme QH(2)-cytochrome c reductase complex in the coq10 cells. Confirming the reduced respiratory chain state in coq10 cells, we found that the expression of the Aspergillus fumigatus alternative oxidase in these cells leads to a decrease in antimycin-dependent H(2)O(2) release and improves their respiratory growth.
Busso
Cleverson
C
Departamento de Microbiologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, Brazil.
Tahara
Erich B
EB
Ogusucu
Renata
R
Augusto
Ohara
O
Ferreira-Junior
Jose Ribamar
JR
Tzagoloff
Alexander
A
Kowaltowski
Alicia J
AJ
Barros
Mario H
MH
D000935:Antifungal Agents / Q000494:pharmacology; D000968:Antimycin A / Q000494:pharmacology*; D001232:Aspergillus fumigatus / Q000201:enzymology / Q000235:genetics; D003574:Cytochrome c Group / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D015151:Immunoblotting; D008689:Methacrylates / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010084:Oxidation-Reduction / Q000187:drug effects; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D010940:Plant Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D000099188:Alternative Oxidase
D000935:Antifungal Agents; D000968:Antimycin A; D003574:Cytochrome c Group; D006861:Hydrogen Peroxide; D008689:Methacrylates; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; D013481:Superoxides; D013844:Thiazoles; D014451:Ubiquinone; D000099188:Alternative Oxidase; C554561:Coq10 protein, S cerevisiae; C030517:myxothiazol; C024989:coenzyme Q10