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Study of barramundi (Lates carcarifer) delta‐6 desaturase and elongase functions and activities using a yeast heterologous expression system
Author(s) -
Tu WeiChun,
James Michael J,
CookJohnson Rebecca J,
Mühlhäusler Beverly S,
Stone David A J,
Gibson Robert A
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.lb184
Subject(s) - barramundi , biochemistry , polyunsaturated fatty acid , fatty acid desaturase , heterologous expression , heterologous , eicosapentaenoic acid , yeast , biology , enzyme , fatty acid , chemistry , food science , fishery , gene , fish <actinopterygii> , lates , recombinant dna
Barramundi are diadromous fish inhabiting the fresh and salt water estuarine regions of northern Australia. Enzymatic capability for conversion of 18 carbon (C18) fatty acids to long chain polyunsaturated fatty acid (LCPUFA) in barramundi was examined. Functional expression was applied to barramundi Δ6 desaturase and elongase genes using yeast heterologous expression system. Results showed that the Δ6 desaturase is not only capable of desaturating α‐linolenic acid (ALA), linoleic acid (LA) and 24:5 n‐3 to their desaturation products but also showed Δ8 desaturase activity. The elongase had a broad range of fatty acid substrate specificity from C18 to C22 PUFA with the greatest activity with eicosapentaenoic acid (EPA). The conversion rate of desaturation was generally lower than elongation. We observed that the apparent desaturation and elongation activities were confounded by the rapid loss of substrates presumably by ß‐oxidation and by the release of desaturation/elongation products to the culture medium. Our findings not only indicate that barramundi have the desaturation and elongation capacity for LCPUFA biosynthesis using dietary ALA and LA as substrates but that because the Δ6 desaturase possesses Δ8 desaturase activity, an alternate route for LCPUFA synthesis exists.