Cloning and characterization of a 2,3-oxidosqualene cyclase from Eleutherococcus trifoliatus

Abstract

Abstract The 2,3-oxidosqualene cyclases (OSCs) are a family of enzymes that have an important role in plant triterpene biosynthesis. In this study, an OSC gene designed EtLUS from Eleutherococcus trifoliatus has been cloned. EtLUS includes a 2292-bp open reading frame and encodes a 763-amino acid protein. EtLUS has an MLCYCR motif, which is conserved in lupeol synthases. Comparison of active-site residues and gene expression in yeast showed that EtLUS synthesizes lupeol. However, EtLUS has the highest sequence identity with β-amyrin synthases from Araliaceae rather than lupeol synthases, adding new perspective to the evolution of the OSCs of Araliaceae. Furthermore, EtLUS is upregulated in leaf tissues under methyl jasmonate treatment, which can be interpreted that lupeol and its derivatives play an ecological and physiological role in plant defense against pathogens and insect herbivores.