Abstract: The diatom Phaeodactylum tricornutum can accumulate eicosapentaenoic acid (EPA) up to 30% of the total fatty acids. This species has been targeted for isolating gene encoding desaturases and elongases for long-chain polyunsaturated fatty acid (LC-PUFA) metabolic engineering. Here we first report the cloning and characterization of Δ5-elongase gene in P. tricornutum. A full-length cDNA sequence, designated PhtELO5, was shown to contain a 1110 bp open reading frame encoding a 369 amino acid polypeptide. The putative protein contains seven transmembrane regions and two elongase characteristic motifs of FLHXYHH and MYSYY, the latter being typical for microalgal Δ5-elongases. Phylogenetic analysis indicated that PhtELO5 belongs to the ELO5 group, tightly clustered with the counterpart of Thalassiosira pseudonana. Heterologous expression of PhtELO5 in Pichia pastoris confirmed that it encodes a specific Δ5-elongase capable of elongating arachidonic acid and eicosapentaenoic acid. Co-expression of PhtELO5 and IsFAD4 (a ∆4-desaturase from Isochrysis sphaerica) demonstrated that the high-efficiency biosynthetic pathway of docosahexaenoic acid was assembled in the transgenic yeast. Substrate competition revealed that PhtELO5 exhibited higher activity towards n-3 PUFA than n-6 PUFA. It is hypothesized that Phaeodactylum ELO5 may preferentially participate in biosynthesis of transgenic LC-PUFA via a n-3 pathway in the yeast host.
Keywords: diatom fatty acids metabolites; Phaeodactylum Δ5-elongase; functional stacking of ELO5 and FAD4
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Jiang, M.; Guo, B.; Wan, X.; Gong, Y.; Zhang, Y.; Hu, C. Isolation and Characterization of the Diatom Phaeodactylum Δ5-Elongase Gene for Transgenic LC-PUFA Production in Pichia pastoris. Mar. Drugs 2014, 12, 1317-1334.
Jiang M, Guo B, Wan X, Gong Y, Zhang Y, Hu C. Isolation and Characterization of the Diatom Phaeodactylum Δ5-Elongase Gene for Transgenic LC-PUFA Production in Pichia pastoris. Marine Drugs. 2014; 12(3):1317-1334.
Jiang, Mulan; Guo, Bing; Wan, Xia; Gong, Yangmin; Zhang, Yinbo; Hu, Chuanjiong. 2014. "Isolation and Characterization of the Diatom Phaeodactylum Δ5-Elongase Gene for Transgenic LC-PUFA Production in Pichia pastoris." Mar. Drugs 12, no. 3: 1317-1334.