|GIDDA, SATINDER - University Of Guelph|
|MULLEN, ROBERT - University Of Guelph|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2010
Publication Date: 5/11/2010
Citation: Gidda, S.K., Shockey, J.M., Mullen, R.T., and Dyer, J.M. (2010). Biogenesis of ER subdomains containing DGAT2, an enzyme involved in industrial oil biosynthesis. Annual Meeting of the American Oil Chemists' Society, May 11 - 16, 2010, Phoenix, AZ.
Technical Abstract: Diacylglycerol acyltransferases (DGATs) are enzymes that catalyze the committed step in triacylglycerol (TAG) biosynthesis by transferring a fatty acyl group from the acyl-CoA pool to the sn-3 position of diacylglycerol. The substrate specificity and overall activity of these enzymes play a key role in determining the quantitative and qualitative properties of seed storage oils. Plants contain two unrelated types of DGAT enzyme called DGAT1 and DGAT2, and we have recently shown that these enzymes have different substrate preferences, that they are located in different regions or “subdomains” of the endoplasmic reticulum (ER), and that DGAT2 plays an important role in the channeling of either conjugated fatty acids or hydroxyl fatty acids into storage oils. The knowledge of DGAT2 subdomain biogenesis, therefore, will likely increase our ability to rationally engineer oilseed crops to produce industrially important oils. Here we describe the identification of two glycerol-3-phosphate acyltransferases (GPATs) from tung (Vernicia fordii) and demonstrate that both proteins target to the same subdomain of ER that is shared by DGAT2. Using a combination of mutational analyses and protein-protein interaction assays, we demonstrate that the GPAT’s first transmembrane-spanning domain, which contains a leucine-zipper-like motif, is responsible for targeting to ER subdomains. These results demonstrate that the enrichment of lipid-biosynthetic enzymes into specific regions of the ER is dependent in part on formation of higher-ordered, oligomeric structures via protein-protein interactions. Implications for oilseed engineering are discussed.