Identification of squalene epoxidase in triterpenes biosynthesis in Poria cocos by molecular docking and CRISPR-Cas9 gene editing.

Background: Squalene epoxidase is one of the rate-limiting enzymes in the biosynthetic pathway of membrane sterols and triterpenoids. The enzyme catalyzes the formation of oxidized squalene, which is a common precursor of sterols and triterpenoids. Result: In this study, the squalene epoxidase gene (PcSE) was evaluated in Poria cocos. Molecular docking between PcSE and squalene was performed and the active amino acids were identified. The sgRNA were designed based on the active site residues. The effect on triterpene synthesis in P. cocos was consistent with the results from ultra-high-performance liquid chromatography-quadruplex time-of-flight-double mass spectrometry (UHPLC-QTOF-MS/MS) analysis. The results showed that deletion of PcSE inhibited triterpene synthesis. In vivo verification of PcSE function was performed using a PEG-mediated protoplast transformation approach. Conclusion: The findings from this study provide a foundation for further studies on heterologous biosynthesis of P. cocos secondary metabolites. Highlights: The gene of squalene epoxidase in P. cocos was identified. Molecular docking was used to predict the amino acid active site of PcSE. Establishment of a CRISPR/Cas9 gene editing system in P. cocos. Function validation of PcSE on triterpene synthesis by gene deletion. [ABSTRACT FROM AUTHOR]