Formation of conjugated Δ810-double bonds by Δ12-oleic-acid desaturase-related enzymes. Biosynthetic origin of calendic acid

Edgar B Cahoon, Kevin G. Ripp, Sarah E. Hall, Anthony J. Kinney

Research output: Contribution to journalArticle

85 Citations (Scopus)

Abstract

Divergent forms of the plant Δ12-oleic-acid desaturase (FAD2) have previously been shown to catalyze the formation of acetylenic bonds, epoxy groups, and conjugated Δ1113-double bonds by modification of an existing Δ12-double bond in C 18 fatty acids. Here, we report a class of FAD2-related enzymes that modifies a Δ9-double bond to produce the conjugated trans-Δ8, trans-Δ10-double bonds found in calendic acid (18:3Δ8trans, 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: 2Δ9cis,12cis). These results are thus consistent with a route of calendic acid synthesis involving modification of the Δ9-double bond of linoleic acid. Regiospecificity for Δ9-double bonds is unprecedented among FAD2-related enzymes and further expands the functional diversity found in this family of enzymes.

Original languageEnglish (US)
Pages (from-to)2637-2643
Number of pages7
JournalJournal of Biological Chemistry
Volume276
Issue number4
DOIs
StatePublished - Jan 26 2001

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Oleic Acid
Calendula
Enzymes
Linoleic Acid
Seeds
Fatty Acids
Embryonic Structures
Oilseeds
Expressed Sequence Tags
Gene Library
Soybeans
Yeast
Saccharomyces cerevisiae
Seed
Amino Acid Sequence
Oils
Complementary DNA
calendic acid
Amino Acids
Peptides

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Formation of conjugated Δ810-double bonds by Δ12-oleic-acid desaturase-related enzymes. Biosynthetic origin of calendic acid. / Cahoon, Edgar B; Ripp, Kevin G.; Hall, Sarah E.; Kinney, Anthony J.

In: Journal of Biological Chemistry, Vol. 276, No. 4, 26.01.2001, p. 2637-2643.

Research output: Contribution to journalArticle

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abstract = "Divergent forms of the plant Δ12-oleic-acid desaturase (FAD2) have previously been shown to catalyze the formation of acetylenic bonds, epoxy groups, and conjugated Δ11,Δ13-double bonds by modification of an existing Δ12-double bond in C 18 fatty acids. Here, we report a class of FAD2-related enzymes that modifies a Δ9-double bond to produce the conjugated trans-Δ8, trans-Δ10-double bonds found in calendic acid (18:3Δ8trans, 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: 2Δ9cis,12cis). These results are thus consistent with a route of calendic acid synthesis involving modification of the Δ9-double bond of linoleic acid. Regiospecificity for Δ9-double bonds is unprecedented among FAD2-related enzymes and further expands the functional diversity found in this family of enzymes.",
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AB - Divergent forms of the plant Δ12-oleic-acid desaturase (FAD2) have previously been shown to catalyze the formation of acetylenic bonds, epoxy groups, and conjugated Δ11,Δ13-double bonds by modification of an existing Δ12-double bond in C 18 fatty acids. Here, we report a class of FAD2-related enzymes that modifies a Δ9-double bond to produce the conjugated trans-Δ8, trans-Δ10-double bonds found in calendic acid (18:3Δ8trans, 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: 2Δ9cis,12cis). These results are thus consistent with a route of calendic acid synthesis involving modification of the Δ9-double bond of linoleic acid. Regiospecificity for Δ9-double bonds is unprecedented among FAD2-related enzymes and further expands the functional diversity found in this family of enzymes.

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