A Specialized Diacylglycerol Acyltransferase Contributes to the Extreme Medium-Chain Fatty Acid Content ofCupheaSeed Oil.
Seed oils of manyCupheasp. contain >90% of medium-chain fatty acids, such as decanoic acid (10:0). These seed oils, which are among the most compositionally variant in the plant kingdom, arise from specialized fatty acid biosynthetic enzymes and specialized acyltransferases. These include lysophosphatidic acid acyltransferases (LPAT) and diacylglycerol acyltransferases (DGAT) that are required for successive acylation of medium-chain fatty acids in thesn-2 andsn-3 positions of seed triacylglycerols (TAGs). Here we report the identification of a cDNA for a DGAT1-type enzyme, designated CpuDGAT1, from the transcriptome ofC. avigeravarpulcherrimadeveloping seeds. Microsomes of camelina (Camelina sativa) seeds engineered for CpuDGAT1 expression displayed DGAT activity with 10:0-CoA and the diacylglycerol didecanoyl, that was approximately 4-fold higher than that in camelina seed microsomes lacking CpuDGAT1. In addition, coexpression in camelina seeds of CpuDGAT1 with aC. viscosissimaFatB thioesterase (CvFatB1) that generates 10:0 resulted in TAGs with nearly 15 mol % of 10:0. More strikingly, expression of CpuDGAT1 and CvFatB1 with the previously described CvLPAT2, a 10:0-CoA-specificCupheaLPAT, increased 10:0 amounts to 25 mol % in camelina seed TAG. These TAGs contained up to 40 mol % 10:0 in thesn-2 position, nearly double the amounts obtained from coexpression of CvFatB1 and CvLPAT2 alone. Although enriched in diacylglycerol, 10:0 was not detected in phosphatidylcholine in these seeds. These findings are consistent with channeling of 10:0 into TAG through the combined activities of specialized LPAT and DGAT activities and demonstrate the biotechnological use of these enzymes to generate 10:0-rich seed oils.
Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (U.I., J.E.S., H.J.K., R.E.C., E.B.C.).|Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden (M.A.); and.|Pervasive Technology Institute and Department of Biology, Indiana University, Bloomington, Indiana 47405 (K.M.).
Umidjon
U
Iskandarov
Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (U.I., J.E.S., H.J.K., R.E.C., E.B.C.).|Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden (M.A.); and.|Pervasive Technology Institute and Department of Biology, Indiana University, Bloomington, Indiana 47405 (K.M.).
Jillian E
JE
Silva
Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (U.I., J.E.S., H.J.K., R.E.C., E.B.C.).|Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden (M.A.); and.|Pervasive Technology Institute and Department of Biology, Indiana University, Bloomington, Indiana 47405 (K.M.).
Hae Jin
http://orcid.org/0000-0001-7456-2127
HJ
Kim
Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (U.I., J.E.S., H.J.K., R.E.C., E.B.C.).|Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden (M.A.); and.|Pervasive Technology Institute and Department of Biology, Indiana University, Bloomington, Indiana 47405 (K.M.).
Mariette
M
Andersson
Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (U.I., J.E.S., H.J.K., R.E.C., E.B.C.).|Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden (M.A.); and.|Pervasive Technology Institute and Department of Biology, Indiana University, Bloomington, Indiana 47405 (K.M.).
Rebecca E
http://orcid.org/0000-0003-3392-5766
RE
Cahoon
Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (U.I., J.E.S., H.J.K., R.E.C., E.B.C.).|Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden (M.A.); and.|Pervasive Technology Institute and Department of Biology, Indiana University, Bloomington, Indiana 47405 (K.M.).
Keithanne
http://orcid.org/0000-0001-6123-8424
K
Mockaitis
Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (U.I., J.E.S., H.J.K., R.E.C., E.B.C.); ecahoon2@unl.edu.|Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden (M.A.); and ecahoon2@unl.edu.|Pervasive Technology Institute and Department of Biology, Indiana University, Bloomington, Indiana 47405 (K.M.) ecahoon2@unl.edu.
Edgar B
http://orcid.org/0000-0002-7277-1176
EB
Cahoon
D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D019607:Brassicaceae / Q000235:genetics / Q000378:metabolism; D031562:Cuphea / Q000235:genetics / Q000378:metabolism*; D051048:Diacylglycerol O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D060847:Metabolic Engineering / Q000379:methods; D010938:Plant Oils / Q000737:chemistry*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D012639:Seeds / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D005227:Fatty Acids; D010938:Plant Oils; D010940:Plant Proteins; D000217:Acyltransferases; D051048:Diacylglycerol O-Acyltransferase; C018764:2-acylglycerophosphate acyltransferase