Seed Fatty Acids, «Front-End»-Desaturases and Chemotaxonomy — a Case Study in the Ranunculaceae

Aitzetmüller, K.; Tsevegsüren, Nansadyn

doi:10.1016/s0176-1617(11)81820-1

Cited by 49 publications

(33 citation statements)

References 7 publications

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“…First, apart from the acyl carrier protein desaturases found in the stroma of higher plant plastids, all fatty acyl desaturases are membrane-bound (2). Second, all desaturases require molecular oxygen and an electron donor (usually cytochrome b 5 or ferredoxin), and finally, the primary deduced amino acid sequences of many diverse desaturases contain highly conserved motifs, namely the three histidine boxes hypothesized to act as di-iron co-ordinating centers (4).…”

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confidence: 99%

“…For example, the presence of an N-terminal cytochrome b 5 domain is considered to be diagnostic for the "front-end" class of desaturases involved in the biosynthesis of long chain polyunsaturated fatty acids (5,6). Equally, mechanistic properties can be used to separate desaturases into those requiring acyl-CoA substrates, and those which utilize glycerolipid-linked substrates (i.e.…”

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confidence: 99%

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A Bifunctional Δ12,Δ15-Desaturase from Acanthamoeba castellanii Directs the Synthesis of Highly Unusual n-1 Series Unsaturated Fatty Acids

Sayanova

Haslam

Guschina

et al. 2006

Journal of Biological Chemistry

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The free-living soil protozoon Acanthamoeba castellanii synthesizes a range of polyunsaturated fatty acids, the balance of which can be altered by environmental changes. We have isolated and functionally characterized in yeast a microsomal desaturase from A. castellanii, which catalyzes the sequential conversion of C 16 and C 18 ⌬9-monounsaturated fatty acids to di-and tri-unsaturated forms. In the case of C 16 substrates, this bifunctional A. castellanii ⌬12,⌬15-desaturase generated a highly unusual fatty acid, hexadecatrienoic acid (16:3⌬ 9,12,15 (n-1)). The identification of a desaturase, which can catalyze the insertion of a double bond between the terminal two carbons of a fatty acid represents a new addition to desaturase functionality and plasticity. We have also co-expressed in yeast the A. castellanii bifunctional ⌬12,⌬15-desaturase with a microsomal ⌬6-desaturase, resulting in the synthesis of the highly unsaturated C 16 fatty acid hexadecatetraenoic acid (16:4⌬ 6,9,12,15 (n-1)), previously only reported in marine microorganisms. Our work therefore demonstrates the feasibility of the heterologous synthesis of polyunsaturated fatty acids of the n-1 series. The presence of a bifunctional ⌬12,⌬15-desaturase in A. castellanii is also considered with reference to the evolution of desaturases and the lineage of this protist.

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A Bifunctional Δ12,Δ15-Desaturase from Acanthamoeba castellanii Directs the Synthesis of Highly Unusual n-1 Series Unsaturated Fatty Acids

Sayanova

Haslam

Guschina

et al. 2006

Journal of Biological Chemistry

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“…The fatty acid desaturases involved in VLC-PUFA biosynthesis can be divided into two groups, the 6-/3-desaturases and the so-called front-end desaturases (7), which contain a cytochrome b 5 -domain fused to their N terminus (8). Whereas the latter group of desaturases inserts the new double bond between the fatty acid carboxyl group and a pre-existing double bond, the 6-/3-desaturases insert it between a pre-existing double bond and the fatty acid methyl end.…”

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Acyl Carriers Used as Substrates by the Desaturases and Elongases Involved in Very Long-chain Polyunsaturated Fatty Acids Biosynthesis Reconstituted in Yeast

Domergue

Abbadi

Ott

et al. 2003

Journal of Biological Chemistry

139

146

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The health benefits attributed to very long-chain polyunsaturated fatty acids and the long term goal to produce them in transgenic oilseed crops have led to the cloning of all the genes coding for the desaturases and elongases involved in their biosynthesis. The encoded activities have been confirmed in vivo by heterologous expression, but very little is known about the actual acyl substrates involved in these pathways. Using a ⌬6-elongase and front-end desaturases from different organisms, we have reconstituted in Saccharomyces cerevisiae the biosynthesis of arachidonic acid from exogenously supplied linoleic acid in order to identify these acyl carriers. Acyl-CoA measurements strongly suggest that the elongation step involved in polyunsaturated fatty acids biosynthesis is taking place within the acyl-CoA pool. In contrast, detailed analyses of lipids revealed that the two desaturation steps (⌬5 and ⌬6) occur predominantly at the sn-2 position of phosphatidylcholine when using ⌬5-and ⌬6-desaturases from lower plants, fungi, worms, and algae. The specificity of these ⌬6-desaturases for the fatty acid acylated at this particular position as well as a limiting re-equilibration with the acyl-CoA pool result in the accumulation of ␥-linolenic acid at the sn-2 position of phosphatidylcholine and prevent efficient arachidonic acid biosynthesis in yeast. We confirm by using a similar experimental approach that, in contrast, the human ⌬6-desaturase uses linoleoyl-CoA as substrate, which results in high efficiency of the subsequent elongation step. In addition, we report that ⌬12-desaturases have no specificity toward the lipid polar headgroup or the sn-position.

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“…Although most edible plant oils are composed of the cisform of unsaturated fatty acids in various proportions, unusual trans-form unsaturated fatty acids are known to be distributed widely in plant seeds 4,5,18 . However, little is known about the dietary effects of natural fats containing trans-Δ3 fatty acids in relation to their biological functions in animals including human.…”

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confidence: 99%

“…The presence of peculiar fatty acids in plants appears to provide clues to the relationship between plant species, genera, or families 4,5 .…”

Section: Introductionmentioning

confidence: 99%

Effects of <i>Aster scaber</i> Seed Oil Containing <i>trans</i>-Δ3 Fatty Acids on Lipid Profiles of Hamsters and Rats

et al. 2015

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Seed Fatty Acids, «Front-End»-Desaturases and Chemotaxonomy — a Case Study in the Ranunculaceae

Cited by 49 publications

References 7 publications

A Bifunctional Δ12,Δ15-Desaturase from Acanthamoeba castellanii Directs the Synthesis of Highly Unusual n-1 Series Unsaturated Fatty Acids

A Bifunctional Δ12,Δ15-Desaturase from Acanthamoeba castellanii Directs the Synthesis of Highly Unusual n-1 Series Unsaturated Fatty Acids

Acyl Carriers Used as Substrates by the Desaturases and Elongases Involved in Very Long-chain Polyunsaturated Fatty Acids Biosynthesis Reconstituted in Yeast

Effects of <i>Aster scaber</i> Seed Oil Containing <i>trans</i>-Δ3 Fatty Acids on Lipid Profiles of Hamsters and Rats

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