Purification, cloning, and bacterial expression of retinol dehydratase from Spodoptera frugiperda

Anhydroretinol and 14-hydroxy-4,14-retro-retinol, retro-retinoids endogenous to both mammals and insects, act as agonist and antagonist, respectively, in controlling proliferation in lymphoblasts and other retinol-dependent cells. We describe here the identification, purification, cloning, and bacterial expression of the enzyme retinol dehydratase, which converts retinol to anhydroretinol in Spodoptera frugiperda. Retinol dehydratase has nanomolar affinity for its substrate and is, therefore, the first enzyme characterized able to utilize free retinol at physiological intracellular concentrations. The enzyme shows sequence homology to the sulfotransferases and requires 3'-phosphoadenosine 5'-phosphosulfate for activity.