Ancient plant-like terpene biosynthesis in corals

Octocorals are major contributors of terpenoid chemical diversity in the ocean. Natural products from other sessile marine animals are primarily biosynthesized by symbiotic microbes rather than by the host. Here we challenge this long-standing paradigm by describing a monophyletic lineage of animal-encoded terpene cyclases (TCs), ubiquitous in octocorals. We characterized 15 TC enzymes from nine genera, several of which produce precursors of iconic, coral-specific terpenoids such as pseudopterosin, lophotoxin and eleutherobin. X-ray crystallography reveals that coral TCs share conserved active site residues and structural features with bacterial TCs. The identification of coral TCs enabled the targeted identification of the enzyme that constructs the coral-exclusive capnellane scaffold. Several TC genes are co-localized with genes that encode enzymes known to modify terpenes. This work presents the first example of biosynthetic capacity in the kingdom Animalia that rivals the chemical complexity generated by plants, unlocking the biotechnological potential of octocorals for biomedical applications.