A diterpene synthase from the clary sage Salvia sclarea catalyzes the cyclization of geranylgeranyl diphosphate to (8R)-hydroxy-copalyl diphosphate

► A cDNA encoding a diterpene synthase from Salvia sclarea has been isolated. ► The recombinant enzyme converts GGPP to (8R)-hydroxy-copalyl diphosphate. ► Hydrolysis of the enzymic reaction with HCl yields (−)-sclareol and 13-epi-sclareol.