title: Increase of eicosapentaenoic acid in thraustochytrids through thraustochytrid ubiquitin promoter-driven expression of a fatty acid {delta}5 desaturase gene.
abstract: Thraustochytrids, marine protists known to accumulate polyunsaturated fatty acids (PUFAs) in lipid droplets, are considered an alternative to fish oils as a source of PUFAs. The major fatty acids produced in thraustochytrids are palmitic acid (C(16:0)), n - 6 docosapentaenoic acid (DPA) (C(22:5)(n) (- 6)), and docosahexaenoic acid (DHA) (C(22:6)(n) (- 3)), with eicosapentaenoic acid (EPA) (C(20:5)(n) (- 3)) and arachidonic acid (AA) (C(20:4)(n) (- 6)) as minor constituents. We attempted here to alter the fatty acid composition of thraustochytrids through the expression of a fatty acid Δ5 desaturase gene driven by the thraustochytrid ubiquitin promoter. The gene was functionally expressed in Aurantiochytrium limacinum mh0186, increasing the amount of EPA converted from eicosatetraenoic acid (ETA) (C(20:4)(n) (- 3)) by the Δ5 desaturase. The levels of EPA and AA were also increased by 4.6- and 13.2-fold in the transgenic thraustochytrids compared to levels in the mock transfectants when ETA and dihomo-γ-linolenic acid (DGLA) (C(20:3)(n) (- 6)) were added to the culture at 0.1 mM. Interestingly, the amount of EPA in the transgenic thraustochytrids increased in proportion to the amount of ETA added to the culture up to 0.4 mM. The rates of conversion and accumulation of EPA were much higher in the thraustochytrids than in baker's yeasts when the desaturase gene was expressed with the respective promoters. This report describes for the first time the finding that an increase of EPA could be accomplished by introducing the Δ5 desaturase gene into thraustochytrids and indicates that molecular breeding of thraustochytrids is a promising strategy for generating beneficial PUFAs.
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan. makotoi@agr.kyushu-u.ac.jp
authors.forename: Takumi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Keishi
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Takanori
authors.initials: T
authors.lastname: Matsuda
authors.forename: Eriko
authors.initials: E
authors.lastname: Abe
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Hama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hayashi
authors.forename: Daiske
authors.initials: D
authors.lastname: Honda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Okita
authors.forename: Shinichi
authors.initials: S
authors.lastname: Sugimoto
authors.forename: Nozomu
authors.initials: N
authors.lastname: Okino
authors.forename: Makoto
authors.initials: M
authors.lastname: Ito
mesh_terms: D000090943:Delta-5 Fatty Acid Desaturase; D015118:Eicosapentaenoic Acid / Q000378:metabolism*; D044943:Fatty Acid Desaturases / Q000096:biosynthesis* / Q000235:genetics; D015870:Gene Expression; D011401:Promoter Regions, Genetic; D058009:Stramenopiles / Q000201:enzymology* / Q000378:metabolism*; D025801:Ubiquitin / Q000235:genetics*
chemical_list: D000090943:Delta-5 Fatty Acid Desaturase; D025801:Ubiquitin; D015118:Eicosapentaenoic Acid; D044943:Fatty Acid Desaturases