Acyl-CoA: lysophosphatidylcholine acyltransferase from diatom P. Tricornutum efficiently remodels phosphatidylcholine containing polyunsaturated fatty acids

This study presents characterisation of diatom's PtLPCAT1 (acyl-CoA: lysophosphatidylcholine acyltransferase) activity in phospholipid remodelling. In this research microsomal fractions of yeast Δale1 mutant overexpressing PtLPCAT1 were used as a source of the tested enzyme. In the assays evaluating remodelling of different phospholipids by PtLPCAT1 not modified microsomal fractions of the tested yeast were used. The enzyme most intensively remodelled fatty acid composition of microsomal phosphatidylcholine (PC), however, it was also able to remodel phosphatidylethanolamine (PE) and phosphatidic acid (PA). To study the ability of the tested enzyme to remodel PC molecules containing fatty acids from the VLC-PUFA biosynthetic pathway the tested microsomes were enriched biochemically with: sn-1-18:1-sn-2-18:3(n-3)-PC, sn-1-18:1-sn-2-18:3(n-6)-PC, sn-1-18:1-sn-2-18:4(n-3)-PC, sn-1-18:1-sn-2-20:4(n-3)-PC and sn-1-18:1-sn-2-20:5(n-3)-PC. Further on it was shown that PtLPCAT1 was able to remodel PC of such modified microsomes with higher intensity than PC of unmodified microsomes. The remodelling efficiency of PtLPCAT1 was affected also by fatty acid donors; the process was most efficient when acyl-CoAs with unsaturated fatty acids were in the assays. In comparative studies the properties of Arabidopsis AtLPCAT1 and yeast ALE1 were tested. Effect of the temperature and pH values on the remodelling activity of PtLPCAT1 was also examined.