Poster: Lipids & Related Molecules

Abs # 852: Functional expression of ricinus communis diacylglycerol acyltransferase in yeast

Presenter:	He, Xiaohua , xiaohua@pw.usda.gov
Authors	He, Xiaohua  (A)   Chen, Grace Q. (A)   Lin, Jiann-Tsyh  (A)   McKeon, Thomas A. (A)
Affiliations:	(A): United states department of agriculture, ars, wrrc

Oil from castor bean (Ricinus communis) contains 90% of hydroxylated fatty acids, these unusual fatty acids are excellent source for producing biodegradeable lubricants and greases. Castor diacylglycerol acyltransferase (RcDGAT) is a critical enzyme, it catalyzes the terminal step in castor oil biosynthesis by preferentially converting 18:1-OH-Diacylglycerol into triricinoleates. A cDNA encoding RcDGAT was isolated from castor seeds. Analysis of the sequence reveals that this cDNA encodes a protein of 521 amino acids with a molecular mass of 59.9 KD. The protein was predicted to have an isoelectric point of 8.39. Expression of the full-length cDNA of RcDGAT in yeast Saccharomyces cerevisiae, strain INVSc1 resulted in a 7-fold higher DGAT activity compared to controls. Southern blot analysis suggested that castor plants contained a single copy of RcDGAT gene and the gene was expressed mainly in the seed tissues. This work will facilitate the investigation of the substrate specificity of RcDGAT and provide the building materials for developing “safer” crops contianing high levels of hydroxylated fatty acids.