title: Biochemical and structural analysis of substrate promiscuity in plant Mg2+-dependent O-methyltransferases.
abstract: Plant S-adenosyl-l-methionine-dependent class I natural product O-methyltransferases (OMTs), related to animal catechol OMTs, are dependent on bivalent cations and strictly specific for the meta position of aromatic vicinal dihydroxy groups. While the primary activity of these class I enzymes is methylation of caffeoyl coenzyme A OMTs, a distinct subset is able to methylate a wider range of substrates, characterized by the promiscuous phenylpropanoid and flavonoid OMT. The observed broad substrate specificity resides in two regions: the N-terminus and a variable insertion loop near the C-terminus, which displays the lowest degree of sequence conservation between the two subfamilies. Structural and biochemical data, based on site-directed mutagenesis and domain exchange between the two enzyme types, present evidence that only small topological changes among otherwise highly conserved 3-D structures are sufficient to differentiate between an enzymatic generalist and an enzymatic specialist in plant natural product methylation.
authors.affiliation: Institut für Biotechnologie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Strasse 3, D-06120 Halle (Saale), Germany.
authors.forename: Jakub G
authors.initials: JG
authors.lastname: Kopycki
authors.forename: Daniel
authors.initials: D
authors.lastname: Rauh
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Chumanevich
authors.forename: Piotr
authors.initials: P
authors.lastname: Neumann
authors.forename: Thomas
authors.initials: T
authors.lastname: Vogt
authors.forename: Milton T
authors.initials: MT
authors.lastname: Stubbs
mesh_terms: D000214:Acyl Coenzyme A / Q000737:chemistry; D000595:Amino Acid Sequence; D001665:Binding Sites; D002109:Caffeic Acids / Q000737:chemistry; D002384:Catalysis; D002867:Chromones / Q000737:chemistry; D018360:Crystallography, X-Ray; D047309:Flavones; D005947:Glucose / Q000737:chemistry; D005960:Glucosides / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry*; D035723:Mesembryanthemum / Q000201:enzymology*; D008745:Methylation; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D011497:Protein O-Methyltransferase / Q000737:chemistry* / Q000235:genetics; D011794:Quercetin / Q000737:chemistry; D013379:Substrate Specificity / Q000235:genetics
chemical_list: D000214:Acyl Coenzyme A; D002109:Caffeic Acids; D002867:Chromones; D047309:Flavones; D005960:Glucosides; D010940:Plant Proteins; C058645:caffeoyl-coenzyme A; D011794:Quercetin; D011497:Protein O-Methyltransferase; D008274:Magnesium; D005947:Glucose; C079163:quercetagetin; C040048:caffeic acid