Plasticity residues involved in secondary cyclization of terpene synthesis in Taiwania cryptomerioides

Abstract

Terpenoids have many biological functions and a comprehensive range of applications. Here, we cloned two monoterpene synthase genes, Tc-αpin/teo and Tc-teo, from Taiwania cryptomerioides. The enzymes encoded by these genes shared 97 % amino acid sequences similarity but had different terpene product profiles. Using structural modeling and site-directed mutagenesis, we successfully identified three plasticity residues around the active site of Tc-αPIN/TEO, namely Y327, Y429 and Y575 that are involved in secondary cyclization. The mutants in which the phenolic residues were replaced with phenylalanines seemed to lose their preference for α-pinene synthesis, indicating that the tyrosine hydroxyl groups at these sites were necessary for the formation of bicyclic terpene products.