Enzymes for lipolysis and fatty acid metabolism in different organelle fractions from rape seed cotyledons

Hoppe, Andreas; Theimer, Roland R.

doi:10.1007/s004250050123

Cited by 15 publications

(8 citation statements)

References 31 publications

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“…In contrast, mammalian mitochondria are capable of complete oxidization of fatty acids to acetyl-CoA (8); the first step of fatty acid ␤-oxidation is accomplished by long-, medium-, and shortchain acyl-CoA dehydrogenases, and electrons generated by the dehydrogenases are transferred to the mitochondrial respiratory chain. By analogy, Thomas and co-workers (9 -11) have postulated the existence of plant mitochondrial ␤-oxidation, but the presence of acyl-CoA dehydrogenase was not investigated or not detected (12). In contrast, data reported by Gerhardt and co-workers (13)(14)(15) have suggested that glyoxysomes in plants can completely metabolize fatty acids to acetyl-CoA.…”

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confidence: 70%

A Novel Acyl-CoA Oxidase That Can Oxidize Short-chain Acyl-CoA in Plant Peroxisomes

Hayashi¹,

Bellis²,

Ciurli³

et al. 1999

Journal of Biological Chemistry

111

102

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Short-chain acyl-CoA oxidases are ␤-oxidation enzymes that are active on short-chain acyl-CoAs and that appear to be present in higher plant peroxisomes and absent in mammalian peroxisomes. Therefore, plant peroxisomes are capable of performing complete ␤-oxidation of acyl-CoA chains, whereas mammalian peroxisomes can perform ␤-oxidation of only those acyl-CoA chains that are larger than octanoyl-CoA (C 8 ). In this report, we have shown that a novel acyl-CoA oxidase can oxidize short-chain acyl-CoA in plant peroxisomes. A peroxisomal short-chain acyl-CoA oxidase from Arabidopsis was purified following the expression of the Arabidopsis cDNA in a baculovirus expression system. The purified enzyme was active on butyryl-CoA (C 4 ), hexanoyl-CoA (C 6 ), and octanoyl-CoA (C 8 ). Cell fractionation and immunocytochemical analysis revealed that the short-chain acyl-CoA oxidase is localized in peroxisomes. The expression pattern of the short-chain acylCoA oxidase was similar to that of peroxisomal 3-ketoacyl-CoA thiolase, a marker enzyme of fatty acid ␤-oxidation, during post-germinative growth. Although the molecular structure and amino acid sequence of the enzyme are similar to those of mammalian mitochondrial acyl-CoA dehydrogenase, the purified enzyme has no activity as acyl-CoA dehydrogenase. These results indicate that the short-chain acyl-CoA oxidases function in fatty acid ␤-oxidation in plant peroxisomes, and that by the cooperative action of long-and short-chain acylCoA oxidases, plant peroxisomes are capable of performing the complete ␤-oxidation of acyl-CoA.Oilseed plants convert reserve oil to sucrose after germination. This unique type of gluconeogenesis occurs in the storage tissues of oilseeds, such as endosperms or cotyledons (1). The metabolic pathway involves many enzymes in several subcellular compartments, including lipid bodies, glyoxysomes (a specialized peroxisome), mitochondria, and the cytosol. Within the entire gluconeogenic pathway, the conversion of a fatty acid to succinate takes place within the glyoxysomes, which contain enzymes for fatty acid ␤-oxidation and the glyoxylate cycle.Glyoxysomes and leaf peroxisomes are members of a group of organelles called peroxisomes (2). In glyoxysomes, fatty acids are first activated to fatty acyl-CoA by fatty acyl-CoA synthetase (3). Fatty acyl-CoA is the substrate for fatty acid ␤-oxidation, which consists of four enzymatic reactions (4). The first reaction is catalyzed by acyl-CoA oxidase. The second and third enzymatic reactions are catalyzed by a single enzyme that possesses enoyl-CoA hydratase and ␤-hydroxyacyl-CoA dehydrogenase activities (5). The fourth reaction is catalyzed by 3-ketoacyl-CoA thiolase (referred to as thiolase below) (6). Acetyl-CoA, an end product of fatty acid ␤-oxidation, is metabolized further to produce succinate by the glyoxylate cycle.In mammalian cells, both peroxisomes and mitochondria contain a functional fatty acid ␤-oxidation system. In peroxisomes, the first enzyme of fatty acid ␤-oxidation, acyl-CoA oxidase, donates...

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confidence: 70%

A Novel Acyl-CoA Oxidase That Can Oxidize Short-chain Acyl-CoA in Plant Peroxisomes

Hayashi¹,

Bellis²,

Ciurli³

et al. 1999

Journal of Biological Chemistry

111

102

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“…This catabolism in higher plants proceeds primarily by peroxisomal ␤-oxidation (Cooper andBeevers, 1969a, 1969b;Gerhardt, 1985), in contrast with mammalian tissues where ␤-oxidation takes place in both peroxisomes and mitochondria. Thus, the existence in higher plants of an additional mitochondrial ␤-oxidation system is often considered controversial (Gerhardt et al, 1995;Hoppe and Theimer, 1997). It is well established that the massive degradation of fatty acids during early growth of fatty seeds proceeds through glyoxysomal ␤-oxidation (Cooper andBeevers, 1969a, 1969b;Hoppe and Theimer, 1997).…”

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confidence: 99%

“…Thus, the existence in higher plants of an additional mitochondrial ␤-oxidation system is often considered controversial (Gerhardt et al, 1995;Hoppe and Theimer, 1997). It is well established that the massive degradation of fatty acids during early growth of fatty seeds proceeds through glyoxysomal ␤-oxidation (Cooper andBeevers, 1969a, 1969b;Hoppe and Theimer, 1997). However, studies of the catabolism of branched-chain amino acids, in which the isobutyryl-CoA, 2-methyl-butyryl-CoA, and isovalerylCoA catabolites of Val, Ile, and Leu, respectively, undergo ␤-oxidation, have led Gerbling and Gerhardt (1989) to hypothesize the existence of extra-peroxisomal ␤-oxidation for Leu and Val degradation.…”

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confidence: 99%

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Identification, Separation, and Characterization of Acyl-Coenzyme A Dehydrogenases Involved in Mitochondrial β-Oxidation in Higher Plants1

Bode

Hooks

Couée³

1999

Plant Physiology

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The existence in higher plants of an additional ␤-oxidation system in mitochondria, besides the well-characterized peroxisomal system, is often considered controversial. Unequivocal demonstration of ␤-oxidation activity in mitochondria should rely on identification of the enzymes specific to mitochondrial ␤-oxidation. Acylcoenzyme A dehydrogenase (ACAD) (EC 1.3.99.2,3) activity was detected in purified mitochondria from maize (Zea mays L.) root tips and from embryonic axes of early-germinating sunflower (Helianthus annuus L.) seeds, using as the enzyme assay the reduction of 2,6-dichlorophenolindophenol, with phenazine methosulfate as the intermediate electron carrier. Subcellular fractionation showed that this ACAD activity was associated with mitochondrial fractions. Comparison of ACAD activity in mitochondria and acylcoenzyme A oxidase activity in peroxisomes showed differences of substrate specificities. Embryonic axes of sunflower seeds were used as starting material for the purification of ACADs. Two distinct ACADs, with medium-chain and long-chain substrate specificities, respectively, were separated by their chromatographic behavior, which was similar to that of mammalian ACADs. The characterization of these ACADs is discussed in relation to the identification of expressed sequenced tags corresponding to ACADs in cDNA sequence analysis projects and with the potential roles of mitochondrial ␤-oxidation in higher plants.

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“…therein;Dieuaide et al 1993;Gerhardt et al 1995;Hoppe and Theimer 1997). Restriction of the b-oxidation activity to peroxisomes in higher plants implies that the peroxisomes are able to degrade completely longchain fatty acids to their constituent acetyl units.…”

Section: Introductionmentioning

confidence: 98%

Glyoxysomal β-oxidation of long-chain fatty acids: completeness of degradation

Kleiter

Gerhardt

1998

Planta

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The ability of glyoxysomes from sun¯ower (Helianthus annuus L.) cotyledons to completely degrade long-chain fatty acids into their constituent acetyl units and the time courses of the appearance of acyl-CoA intermediates during b-oxidation have been studied using 14 C-labelled substrates at non-saturating concentrations (1.3 to 1.8 lmol á l A1 ). [ 14 C]Acetyl-CoA was formed from [18-14 C]oleate metabolized at a yield of up to 80%, and from [U-14 C]palmitate and [U-14 C]linoleate to an extent indicating that a maximum of 80% and 30%, respectively, of the substrate b-oxidized had been degraded beyond the C 4 -CoA intermediate level. To obtain the latter values, an acetyl-CoA-removing system was required during b-oxidation. Constant re-oxidation of the NADH formed during the b-oxidation did not replace the eect of acetyl-CoA removal. Neither the completeness of the linoleate b-oxidation nor the rate of reaction were in¯uenced by NADPH. Medium-and short-chain acyl-CoA intermediates were predominantly detected during b-oxidation of the long-chain substrates employed. The degradation of these intermediates appeared to be stimulated mainly in the presence of an acetyl-CoA-removing system. The time courses of the appearance of intermediates corresponded to a precursor-product relationship between intermediates of decreasing chain lengths.

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Enzymes for lipolysis and fatty acid metabolism in different organelle fractions from rape seed cotyledons

Cited by 15 publications

References 31 publications

A Novel Acyl-CoA Oxidase That Can Oxidize Short-chain Acyl-CoA in Plant Peroxisomes

A Novel Acyl-CoA Oxidase That Can Oxidize Short-chain Acyl-CoA in Plant Peroxisomes

Identification, Separation, and Characterization of Acyl-Coenzyme A Dehydrogenases Involved in Mitochondrial β-Oxidation in Higher Plants1

Glyoxysomal β-oxidation of long-chain fatty acids: completeness of degradation

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