Structural and Functional Studies of Pavine N-Methyltransferase from Thalictrum flavum Reveal Novel Insights into Substrate Recognition and Catalytic Mechanism.

Benzylisoquinoline alkaloids (BIAs) are produced in a wide variety of plants and include many common analgesic, antitussive, and anticancer compounds. Several members of a distinct family of S-adenosylmethionine (SAM)-dependent N-methyltransferases (NMTs) play critical roles in BIA biosynthesis, but the molecular basis of substrate recognition and catalysis is not known for NMTs involved in BIA metabolism. To address this issue, the crystal structure of pavine NMT from Thalictrum flavum was solved using selenomethionine-substituted protein (d = 2.