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. In the present study we show that in plant mitochondria NO may interfere with other respiratory complexes as well. 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-acetyl-DL-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 (Km of 0.77±0.19 to 34.3±5.9 mM, in the 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 non-competitive SDH inhibitor. We suggest that NO inhibits 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.
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Research Article|
December 07 2012
Nitric oxide inhibits succinate dehydrogenase-driven oxygen consumption in potato tuber mitochondria in an oxygen tension-independent manner
Vagner Simonin;
Vagner Simonin
1Laboratório de Bioenergética e Fisiologia Mitocondrial, Programa de Biofísica e Bioquímica Celular, Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Avenida Carlos Chagas Filho, 343, Bloco D SS sala 13, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, CEP 21941-590, Brazil
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Antonio Galina
Antonio Galina
1
1Laboratório de Bioenergética e Fisiologia Mitocondrial, Programa de Biofísica e Bioquímica Celular, Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Avenida Carlos Chagas Filho, 343, Bloco D SS sala 13, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, CEP 21941-590, Brazil
1To whom correspondence should be addressed (email galina@bioqmed.ufrj.br, antoniogalina@yahoo.com.br or galina.antonio@gmail.com).
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Publisher: Portland Press Ltd
Received:
March 06 2012
Revision Received:
October 05 2012
Accepted:
October 08 2012
Accepted Manuscript online:
October 08 2012
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2013 Biochemical Society
2013
Biochem J (2013) 449 (1): 263–273.
Article history
Received:
March 06 2012
Revision Received:
October 05 2012
Accepted:
October 08 2012
Accepted Manuscript online:
October 08 2012
Citation
Vagner Simonin, Antonio Galina; Nitric oxide inhibits succinate dehydrogenase-driven oxygen consumption in potato tuber mitochondria in an oxygen tension-independent manner. Biochem J 1 January 2013; 449 (1): 263–273. doi: https://doi.org/10.1042/BJ20120396
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