Advances in semi-rational design of terpene synthases and their modifying enzymes

As research on natural terpene compounds advances, their pharmacological properties and commercial potential are increasingly recognized. Microbial cell factories offer an efficient means of producing high-value terpene natural products through biosynthesis. However, inherent limitations of native enzymes, such as low catalytic activity and poor stability, have constrained further improvements in production capacity. Recent progress in bioinformatics and the availability of detailed enzyme crystal structures have made semi-rational design a viable and powerful strategy for enhancing the catalytic performance of terpene synthases. This review summarizes semi-rational design strategies applied to key enzymes in the biosynthetic pathways of various terpenes, including mono-, sesqui-, di-, tri-, and tetraterpenes, as well as modifying enzymes such as cytochrome P450s, glycosyltransferases, acetyltransferases, ketolases and hydroxylases involved in terpene biosynthesis. By highlighting recent advances in the functional application of beneficial mutations, it offers a framework for optimizing the catalytic efficiency of enzymes within terpene biosynthesis.