Biotechnology Letters, Vol.36, No.9, 1843-1851, 2014
Coexpression of multiple genes reconstitutes two pathways of very long-chain polyunsaturated fatty acid biosynthesis in Pichia pastoris
The introduction of novel traits to cells often requires the stable coexpression of multiple genes within the same cell. Herein, we report that C-22 very long-chain polyunsaturated fatty acids (VLC-PUFAs) were synthesized from C-18 precursors by reactions catalyzed by delta 6-desaturase, an ELOVL5 involved in VLC-PUFA elongation, and delta 5-desaturase. The coexpression of McD6DES, AsELOVL5, and PtD5DES encoding the corresponding enzymes, produced docosatetraenoic acid (C-22:4 n-6) and docosapentaenoic acid (C-22:5 n-3), as well as arachidonic acid (C-20:4 n-6) and eicosapentaenoic acid (C-20:5 n-3) in the methylotrophic yeast Pichia pastoris. The expression of each gene increased within 24 h, with high transcript levels after induction with 0.5 or 1 % methanol. High levels of the newly expressed VLC-PUFAs occurred after 144 h. This expression system exemplifies the recent progress and future possibilities of the metabolic engineering of VLC-PUFAs in oilseed crops.