Mechanisms and stereochemistry in fatty acid metabolism

Morris, L. J.

doi:10.1042/bj1180681g

Cited by 90 publications

(49 citation statements)

References 32 publications

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“…It has been believed for almost 40 years that its biosynthesis in C. purpurea involves a hydration process that introduced a water molecule into linoleic acid, giving rise to ricinoleic acid Morris, 1970). However, a recent study using deuterium NMR rebutted this hypothesis and showed that the synthesis of ricinoleic acid in C. purpurea follows an oxygendependent hydroxylation process using oleic acid as the substrate (Billault et al, 2004), although the exact nature of the hydroxylase enzyme was not determined.…”

Section: Discussionmentioning

confidence: 86%

“…Although it has long been known that the sclerotia of this fungus produce high levels of ricinoleic acid (Mantle and Nisbet, 1976), the biosynthetic mechanism for fungal production of this fatty acid has not been established. Early reports proposed that biosynthesis of ricinoleic acid in C. purpurea was catalyzed by a hydratase using linoleic acid as a substrate, and did not require molecular oxygen Morris, 1970). This hypothesis has been held for many years.…”

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confidence: 99%

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An Oleate Hydroxylase from the Fungus Claviceps purpurea: Cloning, Functional Analysis, and Expression in Arabidopsis

Meesapyodsuk

Qiu

2008

Plant Physiol.

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Claviceps purpurea, a fungal pathogen responsible for ergot diseases in many agriculturally important cereal crops, produces high levels of ricinoleic acid (12-hydroxyoctadec-cis-9-enoic acid) in its sclerotia. It has been believed for many years that the biosynthesis of this fatty acid in C. purpurea involves a hydration process with linoleic acid as the substrate. Using degenerate polymerase chain reaction, we cloned a gene from the sclerotia encoding an enzyme (CpFAH) that has high sequence similarity to the C. purpurea oleate desaturase, but only low similarity to plant oleate hydroxylases. Functional analysis of CpFAH in yeast (Saccharomyces cerevisiae) indicated it acted predominantly as a hydroxylase, introducing hydroxyl groups at the 12-position of oleic acid and palmitoleic acid. As well, it showed D 12 desaturase activities on 16C and 18C monounsaturated fatty acids and, to a much lesser extent, v 3 desaturase activities on ricinoleic acid. Heterologous expression of CpFAH under the guidance of a seed-specific promoter in Arabidopsis (Arabidopsis thaliana) wild-type and mutant (fad2/fae1) plants resulted in the accumulation of relatively higher levels of hydroxyl fatty acids in seeds. These data indicate that the biosynthesis of ricinoleic acid in C. purpurea is catalyzed by the fungal desaturase-like hydroxylase, and CpFAH, the first D 12 oleate hydroxylase of nonplant origin, is a good candidate for the transgenic production of hydroxyl fatty acids in oilseed crops.

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Section: Discussionmentioning

confidence: 86%

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confidence: 99%

An Oleate Hydroxylase from the Fungus Claviceps purpurea: Cloning, Functional Analysis, and Expression in Arabidopsis

Meesapyodsuk

Qiu

2008

Plant Physiol.

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“…The latter mechanism may account for the ability of B. proteoclasticus, but no other known species, to reduce 18 : 1 fatty acids to 18 : 0 in the rumen. Morris (1970) concluded that the reduction of the cis bond of cis-9-18 : 1 was, like that of cis-9,trans-11-18 : 2, a stereospecific cis addition. Our data do not provide definitive information one way or the other on the mechanism responsible for the metabolism of 18 : 1 fatty acids, but the fact that all three gave the same pattern of M+1/M+2 enrichments suggests that the same enzymic mechanism may be involved.…”

Section: Discussionmentioning

confidence: 99%

Metabolism of conjugated linoleic acids and 18 : 1 fatty acids by ruminal bacteria: products and mechanisms

2010

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Cultures of ruminal bacteria known to metabolize unsaturated fatty acids were grown in medium containing 50 mg ml "1 of geometric and positional isomers of conjugated linoleic acid (CLA) or 18 : 1 fatty acids and 37.4 % deuterium oxide to investigate the mechanisms responsible for fatty acid metabolism. Butyrivibrio fibrisolvens JW11 converted cis-9,trans-11-18 : 2 and trans-9,trans-11-18 : 2 to trans-11-18 : 1 as the main product, labelled at C-9, and metabolized trans-10,cis-12-18 : 2 to trans-10-18 : 1, labelled at C-13, and smaller amounts of trans-12-18 : 1 and cis-12-18 : 1. Butyrivibrio proteoclasticus P-18 did not grow in the presence of cis-9,trans-11-18 : 2 or trans-10,cis-12-18 : 2, but grew in medium containing trans-9,trans-11-18 : 2, forming 18 : 0. Propionibacterium acnes, a ruminal species that isomerizes linoleic acid to trans-10,cis-12-18 : 2, did not metabolize CLA isomers further. B. fibrisolvens metabolized small amounts of trans-10-18 : 1, trans-11-18 : 1 and cis-9-18 : 1, but the products formed were not detected. B. proteoclasticus, on the other hand, carried out substantial conversion of 18 : 1 substrates to 18 : 0. P. acnes hydrated cis-9-18 : 1 and trans-11-18 : 1 to 10-OH-18 : 0, which was further oxidized to yield 10-O-18 : 0. The deuterium enrichment in the intermediates formed during incubations with 9,11 geometric isomers of CLA was about half that of the products from trans-10,cis-12 CLA and 18 : 1 isomers, suggesting that the reduction of 9,11 geometric isomers CLA by ruminal bacteria occurs via different mechanisms compared with the metabolism of other unsaturated fatty acids.

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“…1). Similarly, it has been demonstrated that it is the pro-S position that is retained during desaturation (12)(13)(14). However, to understand the relative impact of these different causes on the observed distribution patterns of 2 H in natural fatty acids, it is necessary to define the quantitative links between different hydrogen positions in the fatty acid and those in the carbohydrate substrates or water from which these have been introduced.…”

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confidence: 99%

Investigation of Fatty Acid Elongation and Desaturation Steps in Fusarium lateritium by Quantitative Two-dimensional Deuterium NMR Spectroscopy in Chiral Oriented Media

Baillif

Robins

Feunteun

et al. 2009

Journal of Biological Chemistry

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The origin of hydrogen atoms during fatty acid biosynthesis in Fusarium lateritium has been quantified by isotope tracking close to natural abundance. Methyl linoleate was isolated from F. lateritium grown in natural abundance medium or in medium slightly enriched with labeled water, glucose, or acetate, and the 2 H incorporation was determined by quantitative 2 H-{ 1 H} NMR in isotropic and chiral oriented solvents. Thus, the individual ( 2 H/ 1 H) i ratio at each pro-R and pro-S hydrogen position of the CH 2 groups along the chain can be analyzed. These values allow the isotope redistribution coefficients (a ij ) that characterize the specific source of each hydrogen atom to be related to the nonexchangeable hydrogen atoms in glucose and to the medium water. In turn, these can be related to the stereoselectivity that operates during the introduction or removal of hydrogens along the fatty acid chain. First, at even CH 2 the pro-S hydrogen comes only from water by protonation, whereas the pro-R hydrogen is introduced partly via acetate but principally from water. Second, the nonexchangeable hydrogens of glucose (positions H-6,6 and H-1) are shown to be introduced to the odd CH 2 via the NAD(P)H pool used by both reductases involved in the elongation steps of the fatty acid chain. Third, it is proved that hydrogens removed at sites 9,10 and 12,13 during desaturation by ⌬ 9 -and ⌬ 12 -desaturases are pro-R, and that during these desaturation steps ␣-secondary kinetic isotope effects occur at the 9 and 12 positions and not at the 10 and 13 positions.Fatty acids are ubiquitous natural products involved in many key biological processes, including acting as components of membranes, as lipophilic modifiers, as fuel stores, and as precursors of intracellular messengers (1-3). Their biosynthesis, which is strictly conserved throughout higher organisms, can be separated into two parts as follows: the formation of the basic C16 unit, palmitoylCoA (C16:1), by the fatty-acid synthase complex (FAS) 2 and the subsequent modification of this chain by a range of elongases, desaturases, conjugases, hydroxylases, and epoxidases. Many of these steps involve stereoselective enzymatic reactions during which hydrogen atoms are inserted or eliminated.We have previously shown that this process leads to a distribution of 2 H in long chain fatty acids that is nonstatistical (4 -7). Thus, isotopic fractionation is seen to be introduced. Two features general to all organisms so far examined can be noted. First, the methylenic groups at even positions tend to be richer than those at odd positions. Second, one of the ethylenic groups present at the positions of desaturation is consistently impoverished relative to the methylenic sites, whereas the other is not.Thus, each hydrogen atom in the final product will have a ( 2 H/ 1 H) ratio that is representative of its initial origin, its passage through the FAS elongation steps, and its potential participation in post-elongation modification of the chain. To date, it has proved possible to exp...

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Mechanisms and stereochemistry in fatty acid metabolism

Cited by 90 publications

References 32 publications

An Oleate Hydroxylase from the Fungus Claviceps purpurea: Cloning, Functional Analysis, and Expression in Arabidopsis

An Oleate Hydroxylase from the Fungus Claviceps purpurea: Cloning, Functional Analysis, and Expression in Arabidopsis

Metabolism of conjugated linoleic acids and 18 : 1 fatty acids by ruminal bacteria: products and mechanisms

Investigation of Fatty Acid Elongation and Desaturation Steps in Fusarium lateritium by Quantitative Two-dimensional Deuterium NMR Spectroscopy in Chiral Oriented Media

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