The availability of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is currently limited because they are produced mainly by marine fisheries that cannot keep pace with the demands of the growing market for these products. A sustainable non-animal source of EPA and DHA is needed. Metabolic engineering of the oleaginous yeast Yarrowia lipolytica resulted in a strain that produced EPA at 15% of dry cell weight. The engineered yeast lipid comprises EPA at 56.6% and saturated fatty acids at less than 5% by weight, which are the highest and the lowest percentages, respectively, among known EPA sources. Inactivation of the peroxisome biogenesis gene PEX10 was crucial in obtaining high EPA yields and may increase the yields of other commercially desirable lipid-related products. This technology platform enables the production of lipids with tailored fatty acid compositions and provides a sustainable source of EPA.
Delta (Δ) 5 desaturase is a key enzyme for the biosynthesis of health-beneficial long chain polyunsaturated fatty acids such as arachidonic acid (ARA, C20:4n-6), eicosapentaenoic acid (C20:5n-3) and docosahexaenoic acid (C22:6n-3) via the “desaturation and elongation” pathways. A full length Δ5 desaturase gene from Euglena gracilis (EgΔ5D) was isolated by cloning the products of polymerase chain reaction with degenerate oligonucleotides as primers, followed by 5′ and 3′ rapid amplification of cDNA ends. The whole coding region of EgΔ5D was 1,350 nucleotides in length and encoded a polypeptide of 449 amino acids. BlastP search showed that EgΔ5D has about 39 % identity with a Δ5 desaturase of Phaeodactylum tricornutum. In a genetically modified dihomo-gamma-linoleic acid (DGLA, C20:3n-6) producing Yarrowia lipolytica strain, EgΔ5D had strong Δ5 desaturase activity with DGLA to ARA conversion of more than 24 %. Functional dissection of its HPGG and HDASH motifs demonstrated that both motifs were important, but not necessary in the exact form as encoded for the enzyme activity of EgΔ5D. A double mutant EgΔ5D-34G158G with altered sequences within both HPGG and HDASH motifs was generated and exhibited Δ5 desaturase activity similar to the wild type EgΔ5D. Codon optimization of the N-terminal region of EgΔ5D-34G158G and substitution of the arginine with serine at residue 347 improved substrate conversion to 27.6 %.Electronic supplementary materialThe online version of this article (doi:10.1007/s11745-012-3690-1) contains supplementary material, which is available to authorized users.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.