[Cloning and expression of a delta6-fatty acid desaturase gene from Rhizopus stolonifer in Saccharomyces cervisiae].
ABSTRACT Fatty acid composition of fungi is analysed through the gas chromatography( GC) technique. With specific activity a novel enzyme delta6-fatty acid desaturase was screened and isolated from Rhizopus stolonifer. In this study R. stolonifer was identified as a fungal species that produced plentiful gamma-linolenic acid. A 1475bp full-length cDNA, designated as RnD6D here, with high homology to fungal delta6-fatty acid desaturase genes was isolated from R. stolonifer using reverse transcription polymerase chain reaction and rapid amplification of cDNA ends methods. Sequence analysis indicated that this cDNA sequence had an open reading frame of 1380bp encoding a deduced polypeptide of 459 amino acids. Bioinformatics analysis characterized the putative RnD6D protein as a typical membrane-bound desaturase, including three conserved histidine-rich motifs, hydropathy profile and a cytochrome b5-like domain in the N-terminus. To elucidate the function of this novel putative desaturase, the coding sequence was expressed in Saccharomyces cerevisiae strain INVScl. A novel peak corresponding to gamma-linolenic acid(GLA) methyl ester standards was detected with the same retention time, which was absent in the cell transformed with empty vector. The percentage of this new GLA was 12.25% of total fatty acids. The result demonstrated that the coding produced delta6-fatty acid desaturase activity of RnD6D which led to the accumulation of gamma-linolenic acid.
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ABSTRACT: The delta 6-desaturase gene was cloned from Rhizopus stolonifer, which could accumulate up to 49% of gamma-linolenic acid (GLA, C18:3 Δ(6,9,12)) to the total fatty acids. The cloned DNA contains a 1,380 bp open reading frame encoding a protein of 460 amino acids, which showed high similarity to those of fungal delta 6-desaturases with three conserved histidine-rich motifs and HPGG motif. Notably, this deduced sequence had a shorter C-terminus. Results demonstrated that the cDNA sequence exhibited delta 6-desaturase activity by accumulation of about 22.4 % of GLA to the total fatty acids in the recombinant Pichia pastoris strain GS115.The Journal of Microbiology 02/2011; 49(1):151-4. · 1.28 Impact Factor