title: A soluble diacylglycerol acyltransferase is involved in triacylglycerol biosynthesis in the oleaginous yeast Rhodotorula glutinis.
abstract: The biosynthesis of triacylglycerol (TAG) occurs in the microsomal membranes of eukaryotes. Here, we report the identification and functional characterization of diacylglycerol acyltransferase (DGAT), a member of the 10 S cytosolic TAG biosynthetic complex (TBC) in Rhodotorula glutinis. Both a full-length and an N-terminally truncated cDNA clone of a single gene were isolated from R. glutinis. The DGAT activity of the protein encoded by RgDGAT was confirmed in vivo by the heterologous expression of cDNA in a Saccharomyces cerevisiae quadruple mutant (H1246) that is defective in TAG synthesis. RgDGAT overexpression in yeast was found to be capable of acylating diacylglycerol (DAG) in an acyl-CoA-dependent manner. Quadruple mutant yeast cells exhibit growth defects in the presence of oleic acid, but wild-type yeast cells do not. In an in vivo fatty acid supplementation experiment, RgDGAT expression rescued quadruple mutant growth in an oleate-containing medium. We describe a soluble acyl-CoA-dependent DAG acyltransferase from R. glutinis that belongs to the DGAT3 class of enzymes. The study highlights the importance of an alternative TAG biosynthetic pathway in oleaginous yeasts.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Sapa Hima
authors.initials: SH
authors.lastname: Rani
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Saikat
authors.initials: S
authors.lastname: Saha
authors.affiliation: Central Food Technological Research Institute, Council of Scientific and Industrial Research, Mysore 570 020, India.|Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Ram
authors.initials: R
authors.lastname: Rajasekharan
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000215:Acylation; D003001:Cloning, Molecular; D016000:Cluster Analysis; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D051048:Diacylglycerol O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D004075:Diglycerides / Q000378:metabolism; D015870:Gene Expression; D008969:Molecular Sequence Data; D010802:Phylogeny; D012248:Rhodotorula / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017422:Sequence Analysis, DNA; D014280:Triglycerides / Q000096:biosynthesis*
chemical_list: D000214:Acyl Coenzyme A; D004271:DNA, Fungal; D004075:Diglycerides; D014280:Triglycerides; D051048:Diacylglycerol O-Acyltransferase