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Abstract Background Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), belonging to ω-3 long-chain polyunsaturated fatty acids (ω3-LC-PUFAs), are essential components of human diet. They are mainly supplemented by marine fish consumption, although their native producers are oleaginous microalgae. Currently, increasing demand for fish oils is insufficient to meet the entire global needs, which puts pressure on searching for the alternative solutions. One possibility may be metabolic engineering of plants with an introduced enzymatic pathway producing ω3-LC-PUFAs. Result In this study we focused on the acyl-CoA:diacylglycerol acyltransferase2b ( Pt DGAT2b) from the diatom Phaeodactylum tricornutum , an enzyme responsible for triacylglycerol (TAG) biosynthesis via acyl-CoA-dependent pathway. Gene encoding Pt DGAT2b, incorporated into TAG-deficient yeast strain H1246, was used to confirm its activity and conduct biochemical characterization. Pt DGAT2b exhibited a broad acyl-CoA preference with both di-16:0-DAG and di-18:1-DAG, whereas di-18:1-DAG was favored. The highest preference for acyl donors was observed for 16:1-, 10:0- and 12:0-CoA. Pt DGAT2b also very efficiently utilized CoA-conjugated ω-3 LC-PUFAs (stearidonic acid, eicosatetraenoic acid and EPA). Additionally, verification of the potential role of Pt DGAT2b in planta , through its transient expression in tobacco leaves, indicated increased TAG production with its relative amount increasing to 8%. Its co-expression with the gene combinations aimed at EPA biosynthesis led to, beside elevated TAG accumulation, efficient accumulation of EPA which constituted even 25.1% of synthesized non-native fatty acids (9.2% of all fatty acids in TAG pool). Conclusions This set of experiments provides a comprehensive biochemical characterization of DGAT enzyme from marine microalgae. Additionally, this study elucidates that Pt DGAT2b can be used successfully in metabolic engineering of plants designed to obtain a boosted TAG level, enriched not only in ω-3 LC-PUFAs but also in medium-chain and ω-7 fatty acids.
Klińska et al. (Tue,) studied this question.