Cloning and functional analysis of Δ6-desaturase gene and its upstream region from Mortierella sp. AGED.

BACKGROUND

Δ6-desaturase belonging to membrane-bound enzyme is a key enzyme involved in the synthesis of polyunsaturated fatty acids (PUFAs). This study aimed to clone and characterise Δ6-desaturase gene and its upstream regulatory region of Mortierella sp. AGED.

RESULTS

Glucose and soybean meal are best for lipid and arachidonic acid accumulation of Mortierella sp. AGED. A 1375-bp Δ6-desaturase gene AGfad6 which contains a 1275-bp open reading frame encoding 424 amino acids without signal peptide was cloned. The putative protein contained three conserved histidine-rich motifs and a conserved cytochrome b5 HPGG (H: Histine, P: Proline, G: Glycine, G: Glycine) motif, with a mass of 48.3 kDa and an isoelectric point of 5.96. AGfad6 was successfully expressed in Pichia pastoris GS115, which exerted the effect on converting linoleic acid to γ-linolenic acid. The 1712-bp upstream region contained basic transcriptional elements including TATA, GC and GATA box, putative target-binding sites for transcription factors such as TATA binding protein, transcription activator, CCAAT-enhancer-binding protein, activator protein 1, alcohol dehydrogenase gene regulator 1 and metabolic regulators p40x in fungi, stress-related elements including GT-1 (light-responsive, salicylic acid-inducible), stress response element, heat stress-responsive element, which might participate in regulation of PUFAs synthesis.

CONCLUSION

The present finding could enable us to understand the evolution and regulatory mechanism of Δ6-desaturase gene.