Cloning of a cDNA encoding diacylglycerol acyltransferase from Arabidopsisthaliana and its functional expression

Triacylglycerols are the most important storage lipids in most plants and a nimals. Acyl-CoA:diacylglycerol acyltransferase (EC 2.3.1.20) catalyzes the final step of the pathway of triacylglycerol synthesis and is the only ste p which is unique to this process. Diacylglycerol acyltransferase is requir ed for the synthesis of storage oil in a wide range of oil-bearing seeds an d fruits and in floral structures such as petals, anthers and pollen. We de scribe the first cloning and functional expression of a cDNA encoding diacy lglycerol acyltransferase from a plant. The cDNA, cloned from Arabidopsis t haliana, encodes a 520 amino acid protein with a predicted molecular mass o f 59.0 kDa which shares 38% amino acid sequence identity with diacylglycero l acyltransferase from mouse. When expressed in insect cell cultures, the p rotein catalyzes the synthesis of [C-14]triacylglycerol from [C-14]diacylgl ycerol and acyl-CoA, Primer extension analysis revealed that the transcript ion begins 225 bases before the translation start site, yielding an unusual ly long 5' untranslated region. The gene is expressed in a wide range of ti ssues but most strongly in developing embryos and petals of flowers, (C) 19 99 Federation of European Biochemical Societies.