The role of mild uncoupling and non‐coupled respiration in the regulation of hydrogen peroxide generation by plant mitochondria

FEBS Letters

Casolo, Valentino¹  Braidot, Enrico¹  Chiandussi, Elisa¹  Macrì, Francesco¹  Vianello, Angelo¹ 

[1]Department of Biology and Agro-Industrial Economics, Section of Plant Biology, University of Udine, via Cotonificio 108, I-33100 Udine, Italy

关键词: Alternative oxidase;    Antioxygen defence;    Hydrogen peroxide;    Plant mitochondria;    Uncoupling;    AAC;    ATP/ADP carrier;    AO;    alternative oxidase;    CAtr;    carboxyatractylate;    ΔΨ;    transmembrane electrical potential;    FCCP;    carbonyl cyanide p-trifluoromethoxyphenylhydrazone;    FFA;    free fatty acids;    ROS;    reactive oxygen species;    UCP;    uncoupling protein;    PUMP;    plant uncoupling mitochondrial protein;   

DOI  :  10.1016/S0014-5793(00)01576-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The roles of mild uncoupling caused by free fatty acids (mediated by plant uncoupling mitochondrial protein (PUMP) and ATP/ADP carrier (AAC)) and non-coupled respiration (alternative oxidase (AO)) on H₂O₂ formation by plant mitochondria were examined. Both laurate and oleate prevent H₂O₂ formation dependent on the oxidation of succinate. Conversely, these free fatty acids (FFA) only slightly affect that dependent on malate plus glutamate oxidation. Carboxyatractylate (CAtr), an inhibitor of AAC, completely inhibits oleate- or laurate-stimulated oxygen consumption linked to succinate oxidation, while GDP, an inhibitor of PUMP, caused only a 30% inhibition. In agreement, CAtr completely restores the oleate-inhibited H₂O₂ formation, while GDP induces only a 30% restoration. Both oleate and laurate cause a mild uncoupling of the electrical potential (generated by succinate), which is then followed by a complete collapse with a sigmoidal kinetic. FFA also inhibit the succinate-dependent reverse electron transfer. Diamide, an inhibitor of AO, favors the malate plus glutamate-dependent H₂O₂ formation, while pyruvate (a stimulator of AO) inhibits it. These results show that the succinate-dependent H₂O₂ formation occurs at the level of Complex I by a reverse electron transport. This generation appears to be prevented by mild uncoupling mediated by FFA. The anionic form of FFA appears to be shuttled by AAC rather than PUMP. The malate plus glutamate-dependent H₂O₂ formation is, conversely, mainly prevented by non-coupled respiration (AO).

【 授权许可】

Unknown