Structure–Activity Relationship of an All-α-helical Prenyltransferase Reveals the Mechanism of Indole Prenylation

Enzymes are involved in the biosynthesis of a variety of secondary metabolites found in nature. The catalytic mechanism is regulated by the three-dimensional structure of the enzyme, particularly at the catalytic site, resulting in the synthesis of natural products with complex conformations derived from a regioselective, chemoselective, or stereoselective preference of the enzyme reaction. Prenyltransferase, which belongs to the prenylsynthase superfamily, catalyzes the condensation of isoprene to an aromatic compound, consequently producing a terpenoid scaffold structure. Prenyltransferase thus plays an important role in expanding the chemical diversity of the terpenoids. Although the three-dimensional structures of prenylsynthases categorized in the same superfamily have been resolved, the catalytic mechanism of prenyltransferase has been veiled. In this study, we determined the X-ray crystal structure of a novel prenyltransferase, Ord1, which is derived from <i>Streptomyces</i>. Here, we report the enzymatic characteristics of the Ord1 and discuss its catalytic mechanism.