title: Identification and characterization of an acyl-CoA:diacylglycerol acyltransferase 2 (DGAT2) gene from the microalga O. tauri.
abstract: In order to identify novel genes encoding enzymes involved in the terminal step of triacylglycerol (TAG) formation, a database search was carried out in the genome of the unicellular photoautotrophic green alga Ostreococcus tauri. The search led to the identification of three putative type 2 acyl-CoA:diacylglycerol acyltransferase-like sequences (DGAT; EC 2.3.1.20), and revealed the absence of any homolog to type 1 or type 3 DGAT sequence in the genome of O. tauri. For two of the cDNA sequences (OtDGAT2A and B) enzyme activity was detected by heterologous expression in Saccharomyces cerevisiae mutant strains with impaired TAG metabolism. However, activity of OtDGAT2A was too low for further analysis. Analysis of their amino acid sequences showed that they share limited identity with other DGAT2 from different plant species, such as Ricinus communis and Vernicia fordii with approximately 25 to 30% identity. Lipid analysis of the mutant yeast cells revealed that OtDGAT2B showed broad substrate specificity accepting saturated as well as mono- and poly-unsaturated acyl-CoAs as substrates.
authors.affiliation: Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wagner
authors.forename: Katharina
authors.initials: K
authors.lastname: Hoppe
authors.forename: Tibor
authors.initials: T
authors.lastname: Czabany
authors.forename: Mareike
authors.initials: M
authors.lastname: Heilmann
authors.forename: Günther
authors.initials: G
authors.lastname: Daum
authors.forename: Ivo
authors.initials: I
authors.lastname: Feussner
authors.forename: Martin
authors.initials: M
authors.lastname: Fulda
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D000460:Chlorophyta / Q000201:enzymology / Q000235:genetics*; D018744:DNA, Plant; D051048:Diacylglycerol O-Acyltransferase / Q000235:genetics*; D005227:Fatty Acids / Q000032:analysis; D015870:Gene Expression; D017343:Genes, Plant; D018745:Genome, Plant; D019684:Magnoliopsida / Q000235:genetics; D009154:Mutation; D012441:Saccharomyces cerevisiae; D017385:Sequence Homology; D013379:Substrate Specificity; D014280:Triglycerides / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D000214:Acyl Coenzyme A; D018744:DNA, Plant; D005227:Fatty Acids; D014280:Triglycerides; D051048:Diacylglycerol O-Acyltransferase