Vibralactone is isolated from the basidiomycete fungus Boreostereum vibrans as one of the strongest lipase inhibitors. Its unusual beta-lactone-fused bicycle is derived from an aryl ring moiety via an oxidative ring-expansion prior to an intramolecular cyclization. Here, we report the discovery of the cyclase VibC which belongs to the alpha/beta-hydrolase superfamily and is involved in the vibralactone biosynthesis. Biochemical and crystal studies suggest that VibC may catalyze an aldol or an electrocyclic reaction initiated by the catalytic Ser-His-Asp triad. For the aldol and pericyclic chemistry in living cells, VibC is a unique hydrolase performing the carbocycle formation of an oxepinone to a fused bicyclic b-lactone. This presents a naturally occurring new enzyme reaction in both aldol and hydrolase (bio)chemistry that will guide future exploitation of these enzymes in synthetic biology for chemical diversity expansion of natural products.
Representative scheme of Hormone-sensitive_lipase_like structure and an image from PDBsum server
Databases
PDB-Sum
6KD0 Previously Class, Architecture, Topology and Homologous superfamily - PDB-Sum server
FSSP
6KD0Fold classification based on Structure-Structure alignment of Proteins - FSSP server
