| A peroxygenase pathway involved in the biosynthesis of epoxy fatty acids in oat. | |
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MedLine Citation:
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PMID: 21784965 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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While oat (Avena sativa) has long been known to produce epoxy fatty acids in seeds, synthesized by a peroxygenase pathway, the gene encoding the peroxygenase remains to be determined. Here we report identification of a peroxygenase cDNA AsPXG1 from developing seeds of oat. AsPXG1 is a small protein with 249 amino acids in length and contains conserved heme-binding residues and a calcium-binding motif. When expressed in Pichia pastoris and Escherichia coli, AsPXG1 catalyzes the strictly hydroperoxide-dependent epoxidation of unsaturated fatty acids. It prefers hydroperoxy-trienoic acids over hydroperoxy-dienoic acids as oxygen donors to oxidize a wide range of unsaturated fatty acids with cis double bonds. Oleic acid is the most preferred substrate. The acyl carrier substrate specificity assay showed phospholipid and acyl-CoA were not effective substrate forms for AsPXG1 and it could only use free fatty acid or fatty acid methyl esters as substrates. A second gene, AsLOX2, cloned from oat codes for a 9-lipoxygenase catalyzing the synthesis of 9-hydroperoxy-dienoic and 9-hydroperoxy-trienoic acids, respectively, when linoleic (18:2-9c,12c) and linolenic (18:3-9c,12c,15c) acids were used as substrates. The peroxygenase pathway was reconstituted in vitro using a mixture of AsPXG1 and AsLOX2 extracts from E. coli. Incubation of methyl oleate and linoleic acid or linolenic acid with the enzyme mixture produced methyl 9,10-epoxy stearate. Incubation of linoleic acid alone with a mixture of AsPXG1 and AsLOX2 produced two major epoxy fatty acids, 9,10-epoxy-12-cis-octadecenoic acid and 12,13-epoxy-9-cis-octadecenoic acid, and a minor epoxy fatty acid, probably 12,13-epoxy-9-hydroxy-10-transoctadecenoic acid. AsPXG1 predominately catalyzes intermolecular peroxygenation. |
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Authors:
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Dauenpen Meesapyodsuk; Xiao Qiu |
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Publication Detail:
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Type: Journal Article Date: 2011-07-22 |
Journal Detail:
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Title: Plant physiology Volume: 157 ISSN: 1532-2548 ISO Abbreviation: Plant Physiol. Publication Date: 2011 Sep |
Date Detail:
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Created Date: 2011-09-05 Completed Date: 2012-01-30 Revised Date: 2012-04-26 |
Medline Journal Info:
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Nlm Unique ID: 0401224 Medline TA: Plant Physiol Country: United States |
Other Details:
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Languages: eng Pagination: 454-63 Citation Subset: IM |
Affiliation:
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Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5A8. |
| Data Bank Information | |
Bank Name/Acc. No.:
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GENBANK/JN390966; JN390967 |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Avena sativa
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metabolism* Base Sequence Cloning, Molecular DNA Primers DNA, Complementary Escherichia coli / genetics Fatty Acids / metabolism* Gas Chromatography-Mass Spectrometry Lipoxygenases / metabolism Mixed Function Oxygenases / genetics, metabolism* Molecular Sequence Data Pichia / genetics Plasmids Substrate Specificity |
| Chemical | |
Reg. No./Substance:
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0/DNA Primers; 0/DNA, Complementary; 0/Fatty Acids; EC 1.-/Mixed Function Oxygenases; EC 1.13.11.-/Lipoxygenases; EC 1.14.-/peroxygenase |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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