PUFA-synthase-specific PPTase enhanced the polyunsaturated fatty acid biosynthesis via the polyketide synthase pathway i

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Biotechnology for Biofuels Open Access

RESEARCH

PUFA‑synthase‑specific PPTase enhanced the polyunsaturated fatty acid biosynthesis via the polyketide synthase pathway in Aurantiochytrium Sen Wang1†, Chuanzeng Lan1,2†, Zhuojun Wang1,2, Weijian Wan1, Qiu Cui1* and Xiaojin Song1* 

Abstract  Background:  Phosphopantetheinyl transferase (PPTase) can change the acyl-carrier protein (ACP) from an inactive apo-ACP to an active holo-ACP that plays a key role in fatty acids biosynthesis. Currently, the PPTase has been proved to be involved in the biosynthesis of polyunsaturated fatty acids (PUFAs) via a polyketide synthase (PKS) pathway in Thraustochytrids, while its characteristics are not clarified. Results:  Here, the heterologous PPTase gene (pfaE) from bacteria was first co-expressed with the PKS system (orfA–orfC) from Thraustochytrid Aurantiochytrium. Then, a new endogenous PPTase (ppt_a) in Aurantiochytrium was identified by homologous alignment and its function was verified in E. coli. Moreover, the endogenous ppt_a was then overexpressed in Aurantiochytrium, and results showed that the production and proportion of PUFAs, especially docosahexaenoic acid (DHA), in the transformant SD116::PPT_A were increased by 35.5% and 17.6%, respectively. Finally, higher DHA and PUFA proportion (53.9% and 64.5% of TFA, respectively) were obtained in SD116::PPT_A using a cerulenin feeding strategy. Conclusions:  This study has illustrated a PUFAs-synthase-specific PPTase in PKS system and provided a new strategy to improve the PUFA production in Thraustochytrids. Keywords:  Aurantiochytrium, DHA, Thraustochytrids, Polyketide synthase, PPTase Background Polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid (DHA, 22:6 ω3) and eicosapentaenoic acid (EPA, 20:5 ω3), are rapidly gaining attention, due to their beneficial effects in the cognitive development *Correspondence: [email protected]; [email protected] † Sen Wang and Chuanzeng Lan have contributed equally to this work 1 CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No.189 Songling Road, Laoshan District, Qingdao 266101, Shandong, China Full list of author information is available at the end of the article

of infants and their use to reduce the risk of hypertension, cardiovascular diseases, inflammation, and certain cancers [1–4]. Currently, the major commercial source of PUFAs is fish oil; however, several factors such as the reduction of marine fish source, the increasing environmental pollution, and undesirable fishy flavor limit the supply of high-quality PUFAs [5, 6]. Therefore, alternative sources of high-quality PUFAs, especially DHA and EPA, have drawn increasing amounts of attention. Heterotrophic thraustochytrids, are capable of accumulating large of lipids, have been increasing embraced by the market [7, 8]. As it is known