Plant diterpene synthases: exploring modularity and metabolic diversity for bioengineering

• Plants use modular pathways to produce thousands of diterpene natural products.
• Diterpenes are used as in pharmaceutical, fragrance, food, and chemical industries.
• Diterpene synthases are key to producing the diversity of diterpene scaffolds.
• Enzyme discovery in plants provides new tools for diterpene metabolic engineering.

Plants produce thousands of diterpenoid natural products; some of which are of significant industrial value as biobased pharmaceuticals (taxol), fragrances (sclareol), food additives (steviosides), and commodity chemicals (diterpene resin acids). In nature, diterpene synthase (diTPS) enzymes are essential for generating diverse diterpene hydrocarbon scaffolds. While some diTPSs also form oxygenated compounds, more commonly, oxygenation is achieved by cytochrome P450-dependent mono-oxygenases. Recent genome-, transcriptome-, and metabolome-guided gene discovery and enzyme characterization identified novel diTPS functions that form the core of complex modular pathway systems. Insights into diterpene metabolism may translate into the development of new bioengineered microbial and plant-based production systems.