6p3m

Tetrahydroprotoberberine N-methyltransferase in complex with S-adenosylhomocysteine

spinqualitylabelsall models 6p3m, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6p3m is a 1 chain structure with sequence from Glaucium flavum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.8Å Ligands: SAH, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Benzylisoquinoline alkaloids (BIAs) are a structurally diverse class of plant specialized metabolites that have been particularly well studied in the order Ranunculales. The N-methyltransferases (NMTs) in BIA biosynthesis can be divided into three groups according to substrate specificity and amino acid sequence. Here, we report the first crystal structures of enzyme complexes from the tetrahydroprotoberberine NMT (TNMT) subclass, specifically for GfTNMT from yellow horned poppy (Glaucium flavum). GfTNMT was co-crystallized with the cofactor S-adenosyl-L-methionine (dmin = 1.6 A), product S-adenosyl-L-homocysteine (dmin = 1.8 A), or in complex with S-adenosyl-L-homocysteine and (S)-cis-N-methylstylopine (dmin = 1.8 A), These structures reveal for the first time how a mostly hydrophobic L-shaped substrate recognition pocket selects for the (S)-cis configuration of the two central six-membered rings in protoberberine BIA compounds. Mutagenesis studies confirm and functionally define the roles of several highly conserved residues within and near the GfTNMT active site. The substrate specificity of TNMT enzymes appears to arise from the arrangement of subgroup-specific stereospecific recognition elements relative to catalytic elements that are more widely conserved among all BIA NMTs. The binding mode of protoberberine compounds to GfTNMT appears to be similar to coclaurine NMT, with the isoquinoline rings buried deepest in the binding pocket. This binding mode differs from that of pavine NMT, in which the benzyl ring is bound more deeply than the isoquinoline rings. The insights into substrate recognition and catalysis provided here form a sound basis for the rational engineering of NMT enzymes for chemoenzymatic synthesis and metabolic engineering. Structure-function studies of tetrahydroprotoberberine N-methyltransferase reveal the molecular basis of stereoselective substrate recognition.,Lang DE, Morris JS, Rowley M, Torres MA, Maksimovich VA, Facchini PJ, Ng KKS J Biol Chem. 2019 Aug 7. pii: RA119.009214. doi: 10.1074/jbc.RA119.009214. PMID:31395658 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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