title: Mitochondrial respiratory electron carriers are involved in oxidative stress during heat stress in Saccharomyces cerevisiae.
abstract: In the present study we sought to determine the source of heat-induced oxidative stress. We investigated the involvement of mitochondrial respiratory electron transport in post-diauxic-phase cells under conditions of lethal heat shock. Petite cells were thermosensitive, had increased nuclear mutation frequencies, and experienced elevated levels of oxidation of an intracellular probe following exposure to a temperature of 50 degrees C. Cells with a deletion in COQ7 leading to a deficiency in coenzyme Q had a much more severe thermosensitivity phenotype for these oxidative endpoints following heat stress compared to that of petite cells. In contrast, deletion of the external NADH dehydrogenases NDE1 and NDE2, which feed electrons from NADH into the electron transport chain, abrogated the levels of heat-induced intracellular fluorescence and nuclear mutation frequency. Mitochondria isolated from COQ7-deficient cells secreted more than 30 times as much H(2)O(2) at 42 as at 30 degrees C, while mitochondria isolated from cells simultaneously deficient in NDE1 and NDE2 secreted no H(2)O(2). We conclude that heat stress causes nuclear mutations via oxidative stress originating from the respiratory electron transport chains of mitochondria.
authors.affiliation: Department of Cancer Cell Biology, Harvard School of Public Health, Boston, MA 02115, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Davidson
authors.forename: R H
authors.initials: RH
authors.lastname: Schiestl
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D004579:Electron Transport; D004583:Electrons; D005609:Free Radicals; D005656:Fungal Proteins / Q000378:metabolism; D017353:Gene Deletion; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D018384:Oxidative Stress; D010101:Oxygen Consumption; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011506:Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013997:Time Factors; D014451:Ubiquinone / Q000235:genetics
chemical_list: D005609:Free Radicals; D005656:Fungal Proteins; D011506:Proteins; D014451:Ubiquinone; D006861:Hydrogen Peroxide