Abstract
Aminoalcoholphosphotransferases (AAPTs) utilize diacylglycerols and CDP-choline/ethanolamine as substrates to synthesize phosphatidylethanolamine (PE) and phosphatidylcholine (PC). We cloned a cDNAs for two AAPTs (TaAAPT1 and TaAAPT2) from a wheat crown. TaAAPT1 and TaAAPT2 complemented the low temperature-sensitive phenotype of the double mutant (Δcpt, Δept) of yeast. Assays with recombinant TaAAPT1 and TaAAPT2 proteins produced in the microsomal fraction of the yeast mutant indicated that TaAAPT1 displayed a greater preference for CDP-ethanolamine than CDP-choline. However, TaAAPT2 mainly utilized CDP-choline. RealTime PCR analysis showed that TaAAPT1 mRNA levels increased in crown tissue during cold treatment, while no increase in TaAAPT2 levels was observed. These results suggest that TaAAPT1 involved in PE biosynthesis is important for cold acclimation of wheat. Fluorescence microscopy images revealed that the TaAAPT1/TaAAPT2::GFP fusion protein are localized in the ER and Golgi apparatus, suggesting that the subcellular sites for the final step of PE/PC synthesis are ER and Golgi apparatus.
