Engineering class I terpene synthases for skeletal diversity: strategies and applications

Abstract

Covering: up to August 2025

Terpenoids constitute nature's largest and most structurally diverse class of natural products, with extensive applications in medicine, agriculture, and fragrance industries. Class I terpene synthases (TSs) create this remarkable diversity by converting linear isoprenoid diphosphates into complex, often polycyclic frameworks through intricate carbocation cascades. This review examines strategies for engineering TSs to generate diverse terpene skeletons—a key objective in synthetic biology. We summarize four core approaches: structure-guided design targeting active sites, water networks, and conserved motifs; evolutionary methods leveraging natural variation and phylogenetic insights; mechanism-focused engineering controlling specific carbocation intermediates; and techniques extending beyond the active site through second-shell modifications and contact mapping. These approaches are complemented by semi-rational and random methods including alanine scanning, saturation mutagenesis, and directed evolution, often enhanced by computational modeling and high-throughput screening. While the complexity of TS catalysis and often weak sequence-function correlations create significant engineering challenges, integration of structural biology, computational simulations, diverse engineering techniques, and advanced screening methods is steadily improving outcomes. Future advances in machine learning, mechanistic understanding, screening technologies, and metabolic engineering integration will further expand access to novel terpenoid chemical space for biotechnological exploration.