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

Sen Wang; Chuanzeng Lan; Zhuojun Wang; Weijian Wan; Qiu Cui; Xiaojin Song

doi:10.1186/s13068-020-01793-x

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

Biotechnol Biofuels. 2020 Aug 31:13:152. doi: 10.1186/s13068-020-01793-x. eCollection 2020.

Authors

Sen Wang^#¹, Chuanzeng Lan^#^{1

2}, Zhuojun Wang^{1

2}, Weijian Wan¹, Qiu Cui¹, Xiaojin Song¹

Affiliations

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.
² University of Chinese Academy of Sciences, Beijing, 100049 China.

^# Contributed equally.

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; PPTase; Polyketide synthase; Thraustochytrids.