Fatty acid beta-oxidation was studied in organellar fractions from maize root tips by h.p.l.c. and radiometric analysis of the products of incubations with [1-14C]octanoate and [1-14C]palmitate. In crude organellar fractions containing both mitochondria and peroxisomes, octanoate and palmitate beta-oxidation, as determined by the production of acetyl-CoA, was functional and, for palmitate, was activated 4-12-fold after subjecting the root tips to 48 h of glucose starvation. The sensitivity to a ‘cocktail’ of respiratory-chain inhibitors containing cyanide, azide and salicylhydroxamate depended on the conditions of incubation, with no inhibition in a medium facilitating peroxisomal beta-oxidation and a significant inhibition in a medium potentially facilitating mitochondrial beta-oxidation. Indeed, preparations of highly purified mitochondria from glucose-starved root tips were able to oxidize octanoate and palmitate to give organic acids of the tricarboxylic acid cycle. This activity was inhibited 5-10-fold by the above cocktail of respiratory-chain inhibitors, with no parallel accumulation of acetyl-CoA, thus showing that the inhibition affected beta-oxidation rather than the pathway from acetyl-CoA to the organic acids. This provides the first evidence that the complete beta-oxidation pathway from fatty acids to citrate was functional in mitochondria from a higher plant. Moreover, an acyl-CoA dehydrogenase activity was shown to be present in the purified mitochondria. In contrast with the peroxisomal activity, mitochondrial beta-oxidation showed the same efficiency with octanoate and palmitate and was strictly dependent on glucose starvation.
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Research Article|
November 15 1993
Effects of glucose starvation on the oxidation of fatty acids by maize root tip mitochondria and peroxisomes: evidence for mitochondrial fatty acid β-oxidation and acyl-CoA dehydrogenase activity in a higher plant
M Dieuaide;
M Dieuaide
1NRA, Centre de Recherche de Bordeaux, Station de Physiologie Végétale, BP 81, 33883 Villenave d'Ornon Cedex, France
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I Couée;
I Couée
1NRA, Centre de Recherche de Bordeaux, Station de Physiologie Végétale, BP 81, 33883 Villenave d'Ornon Cedex, France
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A Pradet;
A Pradet
1NRA, Centre de Recherche de Bordeaux, Station de Physiologie Végétale, BP 81, 33883 Villenave d'Ornon Cedex, France
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P Raymond
P Raymond
1NRA, Centre de Recherche de Bordeaux, Station de Physiologie Végétale, BP 81, 33883 Villenave d'Ornon Cedex, France
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1993 The Biochemical Society, London
1993
Biochem J (1993) 296 (1): 199–207.
Citation
M Dieuaide, I Couée, A Pradet, P Raymond; Effects of glucose starvation on the oxidation of fatty acids by maize root tip mitochondria and peroxisomes: evidence for mitochondrial fatty acid β-oxidation and acyl-CoA dehydrogenase activity in a higher plant. Biochem J 15 November 1993; 296 (1): 199–207. doi: https://doi.org/10.1042/bj2960199
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