Switching on a Nontraditional Enzymatic Base - Deprotonation by Serine in the -Kaurene Synthase from .

Terpene synthases often catalyze complex carbocation cascade reactions. It has been previously shown that single residue switches involving replacement of a key aliphatic residue with serine or threonine can "short-circuit" such reactions, presumed to act indirectly via dipole stabilization of intermediate carbocations. Here a similar switch was found in the structurally characterized -kaurene synthase from . Application of a recently developed computational approach to terpene synthases, , surprisingly indicates direct action of the introduced serine hydroxyl as a catalytic base. Notably, this model suggests alternative interpretation of previous results, and potential routes towards reengineering terpene synthase activity more generally.