title: Analysis of Δ12-fatty acid desaturase function revealed that two distinct pathways are active for the synthesis of PUFAs in T. aureum ATCC 34304.
abstract: Thraustochytrids are known to synthesize PUFAs such as docosahexaenoic acid (DHA). Accumulating evidence suggests the presence of two synthetic pathways of PUFAs in thraustochytrids: the polyketide synthase-like (PUFA synthase) and desaturase/elongase (standard) pathways. It remains unclear whether the latter pathway functions in thraustochytrids. In this study, we report that the standard pathway produces PUFA in Thraustochytrium aureum ATCC 34304. We isolated a gene encoding a putative Δ12-fatty acid desaturase (TauΔ12des) from T. aureum. Yeasts transformed with the tauΔ12des converted endogenous oleic acid (OA) into linoleic acid (LA). The disruption of the tauΔ12des in T. aureum by homologous recombination resulted in the accumulation of OA and a decrease in the levels of LA and its downstream PUFAs. However, the DHA content was increased slightly in tauΔ12des-disruption mutants, suggesting that DHA is primarily produced in T. aureum via the PUFA synthase pathway. The transformation of the tauΔ12des-disruption mutants with a tauΔ12des expression cassette restored the wild-type fatty acid profiles. These data clearly indicate that TauΔ12des functions as Δ12-fatty acid desaturase in the standard pathway of T. aureum and demonstrate that this thraustochytrid produces PUFAs via both the PUFA synthase and the standard pathways.
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.
authors.forename: Takanori
authors.initials: T
authors.lastname: Matsuda
authors.forename: Keishi
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Rie
authors.initials: R
authors.lastname: Hamaguchi
authors.forename: Takumi
authors.initials: T
authors.lastname: Kobayashi
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: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D044943:Fatty Acid Desaturases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017384:Sequence Deletion; D058009:Stramenopiles / Q000201:enzymology / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D005231:Fatty Acids, Unsaturated; D044943:Fatty Acid Desaturases; C040448:delta-12 fatty acid desaturase