The role of C-terminal amino acid residues of a Δ6-fatty acid desaturase from blackcurrant

Delta(6)-fatty acid desaturase is an important enzyme in the catalytic synthesis of polyunsaturated fatty acids. Using domain swapping and a site-directed mutagenesis strategy, we found that the region of the C-terminal 67 amino acid residues of Delta(6)-fatty acid desaturase RnD6C from blackcurrant was essential for its catalytic activity and that seven different residues between RnD6C and RnD8A in that region were involved in the desaturase activity. Compared with RnD6C, the activity of the following mutations, V394A, IC395I, F411L, S436P, VIC3945AI and IS4356VP, was significantly decreased, whereas the activity of 1417T was significantly increased. The amino acids N, T and Y in the last four residues also play a certain role in the desaturase activity. (C) 2013 Elsevier Inc. All rights reserved.