Identification of a Long-Chain Fatty Acid Elongase from Nannochloropsis sp. Involved in the Biosynthesis of Fatty Acids by Heterologous Expression in Saccharomyces cerevisiae

The marine microalga Nannochloropsis sp. contains various elongases and desaturases that are critical for biosynthesis of polyunsaturated fatty acids. A full-length cDNA encoding a long-chain fatty acid elongase, named NsFAE, was cloned from Nannochloropsis sp.. The open reading frame of NsFAE (GenBank accession no. MF680548) consisted of 1068 bp and encoded a predicted protein of 355 amino acids with molecular mass 38.8 kDa. The deduced polypeptide showed 43%–44% identity to fatty acyl elongases from other algae. RT-PCR experiments indicated that the NsFAE gene exhibited the highest expression in Nannochloropsis sp. at 72 h (i.e., during the third growth stage) and the expression was significantly lower in the other four growth stages. Plasmid pNsFAE-CRISPR and a recombinant DNA fragment (ADH₁p-NsFAE-CYCt) were transformed into Saccharomyces cerevisiae strain BY4742 using the CRISPR-Cas system. Yeast transformants containing NsFAE produced three fatty acids not normally present in wild-type BY4742-linoleic acid, linolenic acid and eicosadienoic acid-indicating that NsFAE encodes a functional elongase enzyme.