title: Localization of superoxide anion production to mitochondrial electron transport chain in 3-NPA-treated cells.
abstract: 3-Nitropropionic acid (3-NPA), an inhibitor of succinate dehydrogenase (SDH) at complex II of the mitochondrial electron transport chain induces cellular energy deficit and oxidative stress-related neurotoxicity. In the present study, we identified the site of reactive oxygen species production in mitochondria. 3-NPA increased O2- generation in mitochondria respiring on the complex I substrates pyruvate+malate, an effect fully inhibited by rotenone. Antimycin A increased O2- production in the presence of complex I and/or II substrates. Addition of 3-NPA markedly increased antimycin A-induced O2- production by mitochondria incubated with complex I substrates, but 3-NPA inhibited O2- formation driven with the complex II substrate succinate. At 0.6 microM, myxothiazol inhibits complex III, but only partially decreases complex I activity, and allowed 3-NPA-induced O2- formation; however, at 40 microM myxothiazol (which completely inhibits both complexes I and III) eliminated O2- production from mitochondria respiring via complex I substrates. These results indicate that in the presence of 3-NPA, mitochondria generate O2- from a site between the ubiquinol pool and the 3-NPA block in the respiratory complex II.
authors.affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA.
authors.forename: Attila
authors.initials: A
authors.lastname: Bacsi
authors.forename: Mitchell
authors.initials: M
authors.lastname: Woodberry
authors.forename: William
authors.initials: W
authors.lastname: Widger
authors.forename: John
authors.initials: J
authors.lastname: Papaconstantinou
authors.forename: Sankar
authors.initials: S
authors.lastname: Mitra
authors.forename: Johnny W
authors.initials: JW
authors.lastname: Peterson
authors.forename: Istvan
authors.initials: I
authors.lastname: Boldogh
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D004579:Electron Transport / Q000187:drug effects; D042967:Electron Transport Complex I / Q000378:metabolism; D042963:Electron Transport Complex II / Q000378:metabolism; D006801:Humans; D017737:Macrophages, Peritoneal / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D009574:Nitro Compounds / Q000494:pharmacology*; D011422:Propionates / Q000494:pharmacology*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000037:antagonists & inhibitors; D013481:Superoxides / Q000378:metabolism*; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D009574:Nitro Compounds; D011422:Propionates; D017382:Reactive Oxygen Species; D013481:Superoxides; D014451:Ubiquinone; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D042967:Electron Transport Complex I; C003741:ubiquinol; C015392:3-nitropropionic acid