Expanding the Diversity of the Terpene Skeleton and Structure through Identification of Noncanonical Class IE and IF Terpene Synthase-Formed Products.

Noncanonical class IE and IF terpene synthases have recently been discovered from bacterial genomes through the nonsequence-similarity-based method: protein-structural-model-based genome mining. This study identified the class IE product as a new diterpene comprising the first hydrocarbon skeleton among all terpenoids. The skeleton with a 6/6/6-fused tricyclic structure and six methyl groups could be synthesized through an unprecedented terpene-forming reaction. The class IF product was identified as a new brasilane-type sesquiterpene.