Galina 2012 Abstract Bioblast

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Simonin V, Galina A (2012) Nitric oxide inhibits succinate dehydrogenase-driven oxygen consumption in potato tuber mitochondria in an oxygen tension-independent manner. Mitochondr Physiol Network 17.12.

Link: MiPNet17.12 Bioblast 2012 - Open Access

Simonin V, Galina A (2012)

Event: Bioblast 2012

Antonio Galina

NO (nitric oxide) is described as an inhibitor of plant and mammalian respiratory chains owing to its high affinity for COX (cytochrome c oxidase), which hinders the reduction of oxygen to water [1]. In the present study we show that in plant mitochondria NO may interfere with other respiratory complexes as well [2]. We analysed oxygen consumption supported by complex I and/or complex II and/or external NADH dehydrogenase in Percoll isolated potato tuber (Solanum tuberosum) mitochondria. When mitochondrial respiration was stimulated by succinate, adding the NO donors SNAP (S-nitroso-N-acetylDL-penicillamine) or DETA-NONOate caused a 70% reduction in oxygen consumption rate in state 3 (stimulated with 1 mM of ADP). This inhibition was followed by a significant increase in the Km value of SDH (succinate dehydrogenase) for succinate (K of 0.77+/- 0.19 to 34.3 +/- 5.9 mM, in presence of NO). When mitochondrial respiration was stimulated by external NADH dehydrogenase or complex I, NO had no effect on respiration. NO itself and DETA-NONOate had similar effects to SNAP. No significant inhibition of respiration was observed in the absence of ADP. More importantly, SNAP inhibited PTM (potato tuber mitochondria) respiration independently of oxygen tensions, indicating a different kinetic mechanism from that observed in mammalian mitochondria. We also observed, in an FAD reduction assay, that SNAP blocked the intrinsic SDH electron flow in much the same way as TTFA (thenoyltrifluoroacetone), a non0competitive SDHinhibitor. We suggest that NOinhibits SDH in its ubiquinone site or its Fe–S centres. These data indicate that SDH has an alternative site of NO action in plant mitochondria [3].

  1. Aguirre E, Rodraguez-Juarez F, Bellelli A, Gnaiger E, Cadenas S (2010) Kinetic model of the inhibition of respiration by endogenous nitric oxide in intact cells. Biochim Biophys Acta 1797: 557–565.
  2. Millar AH, Eubel H, Jaensch L, Kruft V, Heazlewood JL, Braun HP (2004) Mitochondrial cytochrome c oxidase and succinate dehydrogenase complexes contain plant specific subunits. Plant Mol Biol 56: 77–90.
  3. Fuentes D, Meneses M, Nunes-Nesi A, Araujo WL, Tapia R, Gomez I, Holuigue L, Gutierrez RA, Fernie AR, Jordana X (2011) A deficiency in the flavoprotein of Arabidopsis mitochondrial complex II results in elevated photosynthesis and better growth in nitrogen-limiting conditions. Plant Physiol 157: 1114–1127. Open Access

Keywords: Plant mitochondria Solanum tuberosum, Nitric oxide

O2k-Network Lab: BR Rio de Janeiro Galina A


Labels:



Enzyme: Complex I, Complex II;succinate dehydrogenase, Complex IV;cytochrome c oxidase 

Coupling state: OXPHOS  Pathway: N, S, NS  HRR: Oxygraph-2k 




Affiliations and author contributions

Vagner Simonin (1), Antonio Galina (1)

(1) Laboratório de Bioenergética e Fisiologia Mitocondrial, Programa de Biofísica e Bioquímica Celular, Instituto de Bioquímica Medica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, Brazil; Email: galina@bioqmed.ufrj.br

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