title: Metabolic engineering of hydroxy fatty acid production in plants: RcDGAT2 drives dramatic increases in ricinoleate levels in seed oil.
abstract: A central goal of green chemistry is to produce industrially useful fatty acids in oilseed crops. Although genes encoding suitable fatty acid-modifying enzymes are available from many wild species, progress has been limited because the expression of these genes in transgenic plants produces low yields of the desired products. For example, Ricinus communis fatty acid hydroxylase 12 (FAH12) produces a maximum of only 17% hydroxy fatty acids (HFAs) when expressed in Arabidopsis. cDNA clones encoding R. communis enzymes for additional steps in the seed oil biosynthetic pathway were identified. Expression of these cDNAs in FAH12 transgenic plants revealed that the R. communis type-2 acyl-coenzyme A:diacylglycerol acyltransferase (RcDGAT2) could increase HFAs from 17% to nearly 30%. Detailed comparisons of seed neutral lipids from the single- and double-transgenic lines indicated that RcDGAT2 substantially modified the triacylglycerol (TAG) pool, with significant increases in most of the major TAG species observed in native castor bean oil. These data suggest that RcDGAT2 prefers acyl-coenzyme A and diacylglycerol substrates containing HFAs, and biochemical analyses of RcDGAT2 expressed in yeast cells confirmed a strong preference for HFA-containing diacylglycerol substrates. Our results demonstrate that pathway engineering approaches can be used successfully to increase the yields of industrial feedstocks in plants, and that members of the DGAT2 gene family probably play a key role in this process.
authors.affiliation: Institute of Biological Chemistry, Clark Hall, Washington State University, Pullman, WA 99164-6340, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Burgal
authors.forename: Jay
authors.initials: J
authors.lastname: Shockey
authors.forename: Chaofu
authors.initials: C
authors.lastname: Lu
authors.forename: John
authors.initials: J
authors.lastname: Dyer
authors.forename: Tony
authors.initials: T
authors.lastname: Larson
authors.forename: Ian
authors.initials: I
authors.lastname: Graham
authors.forename: John
authors.initials: J
authors.lastname: Browse
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D002367:Ricinus communis / Q000201:enzymology* / Q000235:genetics*; D002368:Castor Oil / Q000096:biosynthesis; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D051048:Diacylglycerol O-Acyltransferase / Q000235:genetics*; D015723:Gene Library; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D012277:Ricinoleic Acids / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D012639:Seeds / Q000201:enzymology / Q000235:genetics; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic; D014280:Triglycerides / Q000096:biosynthesis
chemical_list: D000214:Acyl Coenzyme A; D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D012277:Ricinoleic Acids; D014280:Triglycerides; D002368:Castor Oil; D051048:Diacylglycerol O-Acyltransferase