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discounted EARLY registration ends Dec 31, 2014
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discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014

MetaCyc Pathway: hydroxylated fatty acid biosynthesis (plants)

If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Superclasses: Biosynthesis Fatty Acids and Lipids Biosynthesis Fatty Acid Biosynthesis Unusual Fatty Acid Biosynthesis

Some taxa known to possess this pathway include ? : Arabidopsis thaliana col , Lunaria annua , Physaria , Physaria fendleri , Physaria lindheimeri , Ricinus communis

Expected Taxonomic Range: Viridiplantae

Plant oils contribute to the caloric intake of humans and animal. Vegetable oils are extracted from a number of plant sources, soybean oil accounts for nearly 68% of vegetable oil production in the US. Apart from the major use as food, plant oils have several industrial uses. Laurate from coconut oil is extensively used in the manufacture of soaps and detergents. The kinds of fatty acid composition in different seed oils determine the quality and use of the oil.

Plants contain significant amounts of hydroxy fatty acids in their sphingolipids. Castor oil extracted from Ricinus communis contains almost 90% ricinoleate (D-(-)12-hydroxy-octadec-cis-9-enoic acid). The fungus Claviceps purpurea produces Ergot hydroxy fatty acids which are found as esterifed glycerol in triacylglycerols. This esterification extends the ricinoleate molecules through the ester bonds and the resulting lipids are referred to as estolids. Ricinoleate is under large scale production for its uses in a variety of compounds. Pyrolyzation of ricinoleate yields sebacate which is used to produce some types of nylon. Sebacate also finds use as high temperature greases for jet engines. The importance of hydroxylated fatty acids for commercial and nutritional purposes resulted in efforts to develop metabolic engineered pathways for these compounds [Somerville96a, Thelen02].

Ricinoleate occurs throughout the plant kingdom, close relatives of some plants however, are not able to synthesize ricinoleate indicating that the ability to synthesize ricinoleate has had multiple independent origins during evolution. The most enzymes involved in the formation of hydroxylated fatty acids have been characterized from species of the Brassicaceae family which contain a high percentage of hydroxylated fatty acids in their seed oil. The hydroxylated fatty acid biosynthesis takes place at the endoplasmatic reticulum of the cells and includes the microsomal fatty acid elongation (FAE) system [Browse91, Moon01a]. The pathway depicted here represents the conversion of the fatty acid thioesters as the principal metabolic substrates which generally applies to the FAE elongation reactions [Fehling91]. However, it should be mentioned that the respective fatty acids are often esterified to the sn-2 position of the membrane lipid phosphatidylcholin or other phospholipids before further metabolization, i.e. hydroxylation and desaturation can take place [Bafor91, Lin96]. Although acyl-CoA hydrolases exist to release fatty acids from coenzyme A, free fatty acids are considered toxic and therefore not very abundant in plants and unlikely direct reaction partners (Ed Cahoon 2013, personal communication).

The seeds of the genus Physaria (synonym Lesquerella) contain high amounts of hydroxylated fatty acids such as lesquerolate (C20:1Δ11,14OH) and the more desaturated densipolate (C18:2Δ9Δ15, 12OH) and auricolate (C20:2Δ11Δ17, 14OH) [Hayes95, Dierig04] whereas Arabidopsis [Smith00a] and Ricinus [Moreau81] accumulate mainly ricinoleate (18:1Δ9, 12OH). The main biosynthetic route in Physaria is based upon labeling studies [Reed97] and proposes the first formation of ricinoleate by a oleate 12-hydroxylase [Broun98, Dauk07] followed by a desaturase which leads to the formation of densipolate [Broun98, Engeseth96]. The further steps towards the biosynthesis of lesquerolate may occur either through the elongation of ricinoleate or the hydroxylation of (11Z)-eicos-11-enoate [Lin96, Broun97]. The elongation of oleoyl-CoA to form (11Z)-eicos-11-enoyl-CoA has been demonstrated in various species [Fehling91, Moon01a, Ghanevati01]. The final reactions leading to auricolate are unknown and remain to be demonstrated.

Created 15-Feb-2010 by Pujar A , Boyce Thompson Institute
Revised 16-May-2013 by Foerster H , Boyce Thompson Institute


Bafor91: Bafor M, Smith MA, Jonsson L, Stobart K, Stymne S (1991). "Ricinoleic acid biosynthesis and triacylglycerol assembly in microsomal preparations from developing castor-bean (Ricinus communis) endosperm." Biochem J 280 ( Pt 2);507-14. PMID: 1747126

Broun97: Broun P, Somerville C (1997). "Accumulation of ricinoleic, lesquerolic, and densipolic acids in seeds of transgenic Arabidopsis plants that express a fatty acyl hydroxylase cDNA from castor bean." Plant Physiol 113(3);933-42. PMID: 9085577

Broun98: Broun P, Boddupalli S, Somerville C (1998). "A bifunctional oleate 12-hydroxylase: desaturase from Lesquerella fendleri." Plant J 13(2);201-10. PMID: 9680976

Browse91: Browse JP, Somerville CR (1991). "Glycerolipid synthesis: biochemistry and regulation." Annu Rev Plant Physiol Mol Biol 42:467-506.

Dauk07: Dauk M, Lam P, Kunst L, Smith MA (2007). "A FAD2 homologue from Lesquerella lindheimeri has predominantly fatty acid hydroxylase activity." Plant Science 173:43-49.

Dierig04: Dierig DA, Tomasi PM, Salywon AM, Ray DT (2004). "Improvement in hydroxy fatty acid seed oil content and other traits from interspecific hybrids of three Lesquerella species: Lesquerella fendleri, L. pallida, and L. lindheimeri." Euphytica 139:199-206.

Engeseth96: Engeseth N, Stymne S (1996). "Desaturation of oxygenated fatty acids in Lesquerella and other oil seeds." Planta 198:238-245.

Fehling91: Fehling E, Mukherjee KD (1991). "Acyl-CoA elongase from a higher plant (Lunaria annua): metabolic intermediates of very-long-chain acyl-CoA products and substrate specificity." Biochim Biophys Acta 1082(3);239-46. PMID: 2029543

Ghanevati01: Ghanevati M, Jaworski JG (2001). "Active-site residues of a plant membrane-bound fatty acid elongase beta-ketoacyl-CoA synthase, FAE1 KCS." Biochim Biophys Acta 2001;1530(1);77-85. PMID: 11341960

Hayes95: Hayes DG, Kleiman R, Philipps BS (1995). "The triglyceride composition, structure, and presence of estolides in the oils of Lesquerella and related species." J. Am. Oil Chem. Soc. 5: 559-569.

Lin96: Lin JT, McKeon TA, Goodrich-Tanrikulu M, Stafford AE (1996). "Characterization of oleoyl-12-hydroxylase in castor microsomes using the putative substrate, 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine." Lipids 31(6);571-7. PMID: 8784737

Moon01a: Moon H, Smith MA, Kunst L (2001). "A condensing enzyme from the seeds of Lesquerella fendleri that specifically elongates hydroxy fatty acids." Plant Physiol 127(4);1635-43. PMID: 11743108

Moreau81: Moreau RA, Stumpf PK (1981). "Recent studies of the enzymic synthesis of ricinoleic Acid by developing castor beans." Plant Physiol 67(4);672-6. PMID: 16661734

Reed97: Reed DW, Taylor DC, Covello PS (1997). "Metabolism of Hydroxy Fatty Acids in Developing Seeds in the Genera Lesquerella (Brassicaceae) and Linum (Linaceae)." Plant Physiol 114(1);63-68. PMID: 12223689

Smith00a: Smith M, Moon H, Kunst L (2000). "Production of hydroxy fatty acids in the seeds of Arabidopsis thaliana." Biochem Soc Trans 28(6);947-50. PMID: 11171267

Somerville96a: Somerville C, Broun P, Van De Loo FJ (1996). "Production of hydroxylated fatty acids in genetically modified plants." Patent Cooperation Treaty International Appl. No. PCT/ US95 / 11855.

Thelen02: Thelen JJ, Ohlrogge JB (2002). "Metabolic engineering of fatty acid biosynthesis in plants." Metab Eng 4(1);12-21. PMID: 11800570

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Blacklock06: Blacklock BJ, Jaworski JG (2006). "Substrate specificity of Arabidopsis 3-ketoacyl-CoA synthases." Biochem Biophys Res Commun 346(2);583-90. PMID: 16765910

Ghanevati02: Ghanevati M, Jaworski JG (2002). "Engineering and mechanistic studies of the Arabidopsis FAE1 beta-ketoacyl-CoA synthase, FAE1 KCS." Eur J Biochem 269(14);3531-9. PMID: 12135493

James95a: James DW, Lim E, Keller J, Plooy I, Ralston E, Dooner HK (1995). "Directed tagging of the Arabidopsis FATTY ACID ELONGATION1 (FAE1) gene with the maize transposon activator." Plant Cell 1995;7(3);309-19. PMID: 7734965

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Millar97: Millar AA, Kunst L (1997). "Very-long-chain fatty acid biosynthesis is controlled through the expression and specificity of the condensing enzyme." Plant J 12(1);121-31. PMID: 9263455

Oh97: Oh CS, Toke DA, Mandala S, Martin CE (1997). "ELO2 and ELO3, homologues of the Saccharomyces cerevisiae ELO1 gene, function in fatty acid elongation and are required for sphingolipid formation." J Biol Chem 272(28);17376-84. PMID: 9211877

Paul06: Paul S, Gable K, Beaudoin F, Cahoon E, Jaworski J, Napier JA, Dunn TM (2006). "Members of the Arabidopsis FAE1-like 3-ketoacyl-CoA synthase gene family substitute for the Elop proteins of Saccharomyces cerevisiae." J Biol Chem 281(14);9018-29. PMID: 16449229

Rubio06: Rubio S, Larson TR, Gonzalez-Guzman M, Alejandro S, Graham IA, Serrano R, Rodriguez PL (2006). "An Arabidopsis mutant impaired in coenzyme A biosynthesis is sugar dependent for seedling establishment." Plant Physiol 140(3);830-43. PMID: 16415216

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Fri Dec 19, 2014, biocyc14.