Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 2, 2011
Publication Date: August 5, 2011
Citation: Cao, Heping. 2011. Structure-function analysis of diacylglycerol acyltransferase sequences from tung tree and 82 other organisms (abstract). Presented at the 2011 American Society of Plant Biologists Annual Meeting in Minneapolis, Minnesota, August 6-10. http://abstracts.aspb.org/pb2011/public/P02/P02042.html Technical Abstract: Diacylglycerol acyltransferase family (DGATs) catalyzes the final and rate-limiting step of triacylglycerol (TAG) biosynthesis in eukaryotic organisms. DGATs esterify sn-1,2-diacylglycerol with a long-chain fatty acyl-CoA. Understanding the roles of DGATs will help to create transgenic plants with value-added properties and provide information for nutritional and therapeutic intervention for obesity and related diseases. The objective of this analysis was to identify conserved sequence motifs and amino acid residues for better understanding of the structure-function relationship of these important enzymes. 133 DGAT sequences from 83 organisms including plants, animals, fungi and human are analyzed. Phylogenetic analysis separates these proteins into DGAT1 and DGAT2 subfamilies. DGATs are integral membrane proteins with ~40% of the amino acid residues being hydrophobic. They have similar properties and amino acid composition except that DGAT1s are ~18 kDa larger than DGAT2s. DGAT1s and DGAT2s have 41 and 15 completely conserved amino acid residues, respectively, although only two residues are completely conserved among all DGATs. These residues are distributed in 7 and 6 sequence blocks of DGAT1s and DGAT2s, respectively, and located at the carboxyl termini, suggesting the location of the catalytic domains. These conserved sequence blocks do not contain the putative neutral lipid-binding domain, mitochondrial targeting signal, or ER retrieval motif. The importance of some conserved residues in TAG biosynthesis has been demonstrated by natural and site-directed mutants. The sequence analysis should facilitate studying the structure-function relationship of DGATs with the ultimate goal to identify critical amino acid residues for metabolic engineering and drug discovery.