Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 2009
Publication Date: December 4, 2009
Citation: Gidda, S.K., Shockey, J.M., Dyer, J.M., and Mullen, R.T. (2009). Biogenesis of glycerol 3-phosphate acyltransferase (GPAT): influence of transmembrane domains and protein-protein interactions on the localization of GPAT to ER subdomains. Eastern Regional Meeting of the Canadian Society of Plant Physiologists, December 4 - 5, 2009, Guelph, Ontarion, Canada. Technical Abstract: Glycerolipids are the major components of cellular membranes in all plant cells, storage oils in developing seeds, and the cuticular surface of plant organs. Using the tung (Vernicia fordii) triacylglycerol (TAG) biosynthetic enzymes as model system, we previously showed that the type 1 and 2 diacylglycerol acyltransferase (DGAT1 and DGAT2) involved in the committed step of TAG biosynthesis are located in distinct subdomains of the ER [Shockey et al. 2006. Plant Cell 18:2294]. Here, we describe some of the cellular properties of the enzymes that mediate the initial step in the production of glycerolipids, glycerol-3-phosphate acyltransferases (GPATs). For instance, we show that both GPAT8 and GPAT9, a newly-identified GPAT with homology to mammalian GPAT3, are localized to the same ER subdomain as DGAT2. Split-ubiquitin yeast-two hybrid assays revealed that GPAT8, GPAT9 and DGAT2, but not DGAT1, physically interact and comprehensive mutational analysis of GPAT8 revealed that the protein’s two transmembrane domains (TMDs) and intervening loop region are both necessary and sufficient for localization to the ER subdomain. The implications of these results in terms of understanding of the regulation and organization of glycerolipid biosynthesis and the formation of ER subdomains via high-ordered, protein homo- and hetero-oligomeric complexes are discussed.