Cloning and functional characterisation of a fatty acyl elongase from southern bluefin tuna (Thunnus maccoyii).

Melissa Gregory, Valene See, Robert Gibson, Kathryn Schuller

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    56 Citations (Scopus)

    Abstract

    The synthesis of long chain polyunsaturated fatty acids (LCPUFA), such as eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), involves fatty acyl desaturase and elongase enzymes. The marine fish species southern bluefin tuna (SBT) can accumulate large quantities of omega-3 (n-3) LCPUFA in its flesh but their capacity to synthesize EPA and DHA is uncertain. A cDNA, sbtElovl5, encoding a putative fatty acyl elongase was amplified from SBT liver tissue. The cDNA included an open reading frame (ORF) encoding 294 amino acids. Sequence comparisons and phylogenetic analyses revealed a high level of sequence conservation between sbtElovl5 and fatty acyl elongase sequences from other fish species. Heterologous expression of the sbtElovl5 ORF in Saccharomyces cerevisiae confirmed that it encoded a fatty acyl elongase capable of elongating C18/20 polyunsaturated fatty acid (PUFA) substrates, but not C22 PUFA substrates. For the first time in an Elovl5, the substrate competition occurring in nature was investigated. Higher activity towards n-3 PUFA substrates than omega-6 (n-6) PUFA substrates was exhibited, regardless of substrate chain length. The sbtElovl5 preferentially elongated 18:4n-3 and 18:3n-6 rather than 20:5n-3 and 20:4n-6. The sbtElovl5 enzyme also elongated saturated and monounsaturated fatty acids. Crown

    Original languageEnglish
    Pages (from-to)178-185
    Number of pages8
    JournalComparative Biochemistry and Physiology B-Biochemistry and Molecular Biology
    Volume155
    Issue number2
    DOIs
    Publication statusPublished - Feb 2010

    Keywords

    • Aquaculture
    • cDNA
    • Fatty acyl elongase
    • Long chain polyunsaturated fatty acids
    • Southern bluefin tuna
    • Yeast expression

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