title: Detection of genes involved in fatty acid elongation and desaturation in thraustochytrid marine eukaryotes.
abstract: Heterotrophic marine protists known as thraustochytrids can synthesize polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA). The biosynthetic pathways of PUFAs in thraustochytrids are poorly understood, however. In this study, we attempted to reveal the enzymes involved in DHA synthesis in thraustochytrids. Nine thraustochytrid strains representing 3 genera (Aurantiochytrium, Schizochytrium, and Thraustochytrium) were used for PCR-based detection of the genes encoding Δ5-elongase and Δ4-desaturase and for fatty acid analysis. The degenerate primers were designed to amplify the Δ5-elongase and Δ4-desaturase genes, and the partial sequences of the enzymes were obtained from the genera Thraustochytrium and Schizochytrium. These fragments were identical to those of known Δ5-elongase and Δ4-desaturase. Neither Δ5-elongase nor Δ4-desaturase was detected in the strains belonging to the genus Aurantiochytrium, however, suggesting that this group likely synthesizes DHA not via the elongation/desaturation pathway but via an alternate pathway such as the polyketide synthase pathway. The fatty acid profiles of thraustochytrids were consistent with the presence of genes involved in PUFA biosynthesis in thraustochytrid genera. Thus, our findings suggest that two biosynthetic pathways for PUFAs exist in these organisms.
authors.affiliation: Department of Marine Biology and Environmental Sciences, Faculty of Agriculture, University of Miyazaki.
authors.forename: Naoki
authors.initials: N
authors.lastname: Nagano
authors.forename: Keishi
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Taoka
authors.forename: Yuji
authors.initials: Y
authors.lastname: Okita
authors.forename: Daiske
authors.initials: D
authors.lastname: Honda
authors.forename: Makoto
authors.initials: M
authors.lastname: Ito
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hayashi
mesh_terms: D000123:Acetyltransferases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism; D000081031:Fatty Acid Elongases; D005231:Fatty Acids, Unsaturated / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D058009:Stramenopiles / Q000201:enzymology* / Q000378:metabolism*
chemical_list: D005231:Fatty Acids, Unsaturated; D044943:Fatty Acid Desaturases; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases