Document Detail

Formation of conjugated delta8,delta10-double bonds by delta12-oleic-acid desaturase-related enzymes: biosynthetic origin of calendic acid.
MedLine Citation:
PMID:  11067856     Owner:  NLM     Status:  MEDLINE    
Divergent forms of the plant Delta(12)-oleic-acid desaturase (FAD2) have previously been shown to catalyze the formation of acetylenic bonds, epoxy groups, and conjugated Delta(11),Delta(13)-double bonds by modification of an existing Delta(12)-double bond in C(18) fatty acids. Here, we report a class of FAD2-related enzymes that modifies a Delta(9)-double bond to produce the conjugated trans-Delta(8),trans-Delta(10)-double bonds found in calendic acid (18:3Delta(8trans,10trans,12cis)), the major component of the seed oil of Calendula officinalis. Using an expressed sequence tag approach, cDNAs for two closely related FAD2-like enzymes, designated CoFADX-1 and CoFADX-2, were identified from a C. officinalis developing seed cDNA library. The deduced amino acid sequences of these polypeptides share 40-50% identity with those of other FAD2 and FAD2-related enzymes. Expression of either CoFADX-1 or CoFADX-2 in somatic soybean embryos resulted in the production of calendic acid. In embryos expressing CoFADX-2, calendic acid accumulated to as high as 22% (w/w) of the total fatty acids. In addition, expression of CoFADX-1 and CoFADX-2 in Saccharomyces cerevisiae was accompanied by calendic acid accumulation when induced cells were supplied exogenous linoleic acid (18:2Delta(9cis,12cis)). These results are thus consistent with a route of calendic acid synthesis involving modification of the Delta(9)-double bond of linoleic acid. Regiospecificity for Delta(9)-double bonds is unprecedented among FAD2-related enzymes and further expands the functional diversity found in this family of enzymes.
E B Cahoon; K G Ripp; S E Hall; A J Kinney
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2000-11-06
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  276     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2001 Jan 
Date Detail:
Created Date:  2001-05-23     Completed Date:  2001-06-21     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2637-43     Citation Subset:  IM    
DuPont Nutrition and Health, Experimental Station, Wilmington, Delaware 19880-0402, USA.
Data Bank Information
Bank Name/Acc. No.:
GENBANK/AF310155;  AF310156
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MeSH Terms
Amino Acid Sequence
Calendula / enzymology*,  genetics
Cloning, Molecular
Fatty Acid Desaturases / genetics,  metabolism*
Fatty Acids, Unsaturated / biosynthesis*
Gene Library
Linoleic Acid / metabolism
Molecular Sequence Data
Oleic Acid / metabolism
Plant Proteins / genetics,  metabolism
Plants, Genetically Modified
Plants, Medicinal*
Seeds / enzymology,  genetics
Sequence Homology, Amino Acid
Soybeans / genetics
Reg. No./Substance:
0/Fatty Acids, Unsaturated; 0/Plant Proteins; 112-80-1/Oleic Acid; 2197-37-7/Linoleic Acid; 5204-87-5/calendic acid; EC 1.14.19.-/Fatty Acid Desaturases; EC 1.14.99.-/FADX-1 protein, Calendula officinalis; EC 1.14.99.-/FADX-2 protein, Calendula officinalis; EC 1.14.99.-/delta-12 fatty acid desaturase

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