title: Nitrite-driven anaerobic ATP synthesis in barley and rice root mitochondria.
abstract: Mitochondria isolated from the roots of barley (Hordeum vulgare L.) and rice (Oryza sativa L.) seedlings were capable of oxidizing external NADH and NADPH anaerobically in the presence of nitrite. The reaction was linked to ATP synthesis and nitric oxide (NO) was a measurable product. The rates of NADH and NADPH oxidation were in the range of 12-16 nmol min(-1) mg(-1) protein for both species. The anaerobic ATP synthesis rate was 7-9 nmol min(-1) mg(-1) protein for barley and 15-17 nmol min(-1) mg(-1) protein for rice. The rates are of the same order of magnitude as glycolytic ATP production during anoxia and about 3-5% of the aerobic mitochondrial ATP synthesis rate. NADH/NADPH oxidation and ATP synthesis were sensitive to the mitochondrial inhibitors myxothiazol, oligomycin, diphenyleneiodonium and insensitive to rotenone and antimycin A. The uncoupler FCCP completely eliminated ATP production. Succinate was also capable of driving ATP synthesis. We conclude that plant mitochondria, under anaerobic conditions, have a capacity to use nitrite as an electron acceptor to oxidize cytosolic NADH/NADPH and generate ATP.
authors.affiliation: Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
authors.forename: Maria
authors.initials: M
authors.lastname: Stoimenova
authors.forename: Abir U
authors.initials: AU
authors.lastname: Igamberdiev
authors.forename: Kapuganti Jagadis
authors.initials: KJ
authors.lastname: Gupta
authors.forename: Robert D
authors.initials: RD
authors.lastname: Hill
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000693:Anaerobiosis; D001467:Hordeum / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000378:metabolism; D012275:Oryza / Q000378:metabolism*; D010084:Oxidation-Reduction; D018517:Plant Roots / Q000378:metabolism
chemical_list: D009573:Nitrites; D009589:Nitrogen Oxides; D009243:NAD; D009249:NADP; D000255:Adenosine Triphosphate