This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: arachidonic acid biosynthesis
|Superclasses:||Biosynthesis → Fatty Acids and Lipids Biosynthesis → Fatty Acid Biosynthesis → Unusual Fatty Acid Biosynthesis|
Polyunsaturated long chain fatty acids (PUFAs) have18 or more carbon atoms containing more than one double bond in its backbone. The PUFAs that have 2 or more cis double bonds separated from each other by a single methylene group generally belong to the essential fatty acids which are all either ω3 or ω6 methylene interrupted fatty acids. PUFAs accumulate in many algae, mosses and ferns, where they are found in all major glycerol lipids and represent major constituents of membranes [Kaewsuwan06]. These compounds are not commonly found in higher plants, which typically produce saturated and mono-unsaturated long chain fatty acids as common constituents of the plant cuticle.
Arachidonic acid is a C20 PUFA (20:4Δ5,8,11,14) that is produced at high levels by the moss Physcomitrella patens. Physcomitrella patens also produces lower amounts of of the C20 PUFA (5Z,8Z,11Z,14Z,17Z)-icosapentaenoate (20:5Δ5,8,11,14,17).
About this Pathway
The biosynthesis of arachidonate and (5Z,8Z,11Z,14Z,17Z)-icosapentaenoate in the moss Physcomitrella patens starts with linoleate (18:2Δ9,12) and α-linolenate(18:3Δ9,12,15), respectively, and involves sequential Δ6 desaturation, Δ6 elongation, and a Δ5 desaturation. Acyl-CoA thioesters are required for desaturases and elongases involved in long chain polyunsaturated fatty acids biosynthesis [Domergue03]. Fatty acid elongase complexes comprise of the β-keto-acyl-CoA synthase, ketoacyl-CoA reductase, hydroxyacyl-CoA reductase and the enoyl-CoA reductase enzyme activities [Meyer04].
A Δ6 acyl-group desaturase was previously identified and cloned in Physcomitrella patens [Girke98], as was a Δ6 elongase [Zank02]. The most recent discovery in the elucidation of the pathway was the identification of the Δ5 desaturase in this organism. The Δ5 and Δ6 desaturases introduce the new double bonds between the first double bond and the carboxyl end of the fatty acid, in a mechanism known as carboxyl-directed desaturation. It differs from methyl-directed desaturation, where the introduction of double bonds is directed by the methyl end of the fatty acid. See also eicosapentaenoate biosynthesis I (algae and lower plants).
Created 27-Sep-2006 by Zhang P , TAIR
Revised 25-Oct-2011 by Weerasinghe D , SRI International
Revised 22-Nov-2011 by Caspi R , SRI International
Revised 23-Jan-2012 by Weerasinghe D , SRI International
Revised 22-May-2012 by Weerasinghe D , SRI International
Domergue03: Domergue F, Abbadi A, Ott C, Zank TK, Zahringer U, Heinz E (2003). "Acyl carriers used as substrates by the desaturases and elongases involved in very long-chain polyunsaturated fatty acids biosynthesis reconstituted in yeast." J Biol Chem 278(37);35115-26. PMID: 12835316
Girke98: Girke T, Schmidt H, Zahringer U, Reski R, Heinz E (1998). "Identification of a novel delta 6-acyl-group desaturase by targeted gene disruption in Physcomitrella patens." Plant J 15(1);39-48. PMID: 9744093
Kaewsuwan06: Kaewsuwan S, Cahoon EB, Perroud PF, Wiwat C, Panvisavas N, Quatrano RS, Cove DJ, Bunyapraphatsara N (2006). "Identification and functional characterization of the moss Physcomitrella patens delta5-desaturase gene involved in arachidonic and eicosapentaenoic acid biosynthesis." J Biol Chem 281(31);21988-97. PMID: 16728405
Meyer04: Meyer A, Kirsch H, Domergue F, Abbadi A, Sperling P, Bauer J, Cirpus P, Zank TK, Moreau H, Roscoe TJ, Zahringer U, Heinz E (2004). "Novel fatty acid elongases and their use for the reconstitution of docosahexaenoic acid biosynthesis." J Lipid Res 45(10);1899-909. PMID: 15292371
Zank02: Zank TK, Zahringer U, Beckmann C, Pohnert G, Boland W, Holtorf H, Reski R, Lerchl J, Heinz E (2002). "Cloning and functional characterisation of an enzyme involved in the elongation of Delta6-polyunsaturated fatty acids from the moss Physcomitrella patens." Plant J 31(3);255-68. PMID: 12164806
Malhotra99: Malhotra KT, Malhotra K, Lubin BH, Kuypers FA (1999). "Identification and molecular characterization of acyl-CoA synthetase in human erythrocytes and erythroid precursors." Biochem J 344 Pt 1;135-43. PMID: 10548543
Reddy93: Reddy AS, Nuccio ML, Gross LM, Thomas TL (1993). "Isolation of a delta 6-desaturase gene from the cyanobacterium Synechocystis sp. strain PCC 6803 by gain-of-function expression in Anabaena sp. strain PCC 7120." Plant Mol Biol 22(2);293-300. PMID: 8389613
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
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