Open AccessΔ 9 ‐Fatty acid desaturase from arachidonic acid‐producing fungus
Author(s) -
Sakuradani Eiji,
Kobayashi Michihiko,
Shimizu Sakayu
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00131.x
Subject(s) - palmitoleic acid , biochemistry , biology , aspergillus oryzae , arachidonic acid , oleic acid , complementary dna , stearic acid , fatty acid desaturase , linoleic acid , palmitic acid , fatty acid , gene , microbiology and biotechnology , chemistry , polyunsaturated fatty acid , enzyme , organic chemistry
Based on the sequence information for Δ 9 ‐desaturase genes (from rat, mouse and yeast), which are involved in the desaturation of palmitic acid and stearic acid to palmitoleic acid and oleic acid, respectively, the corresponding cDNA and genomic gene were cloned from the fungal strain, Mortierella alpina 1S‐4, which industrially produces arachidonic acid. There was a cytochrome b 5 ‐like domain linked to the carboxyl terminus of this Mortierella desaturase, as also seen in the yeast Δ 9 ‐desaturase. The Mortierella Δ 9 ‐desaturase genomic gene had only one intron, in which a novel phenomenon was observed: there was a GC‐end at the 5′‐terminus instead of a GT‐end that is, in general, found in introns of eukaryotic genes. The full‐length cDNA clone was expressed under the control of an amyB promoter in a filamentous fungus, Aspergillus oryzae , resulting in drastic changes in the fatty acid composition in the transformant cells; the contents of palmitoleic acid (16 : 1) and oleic acid (18 : 1) increased significantly, with accompanying decreases in palmitic acid (16 : 0) and stearic acid (18 : 0). These changes were controlled by the addition of maltose as a carbon source to the medium. Also, the expression of the gene caused a significant change in the lipid composition in the Aspergillus transformant. Genomic Southern blot analysis of the transformant with the Mortierella Δ 9 ‐desaturase gene as a probe confirmed the integration of this gene into the genome of A. oryzae .