title: Evolution of novel O-methyltransferases from the Vanilla planifolia caffeic acid O-methyltransferase.
abstract: The biosynthesis of many plant secondary compounds involves the methylation of one or more hydroxyl groups, catalyzed by O-methyltransferases (OMTs). Here, we report the characterization of two OMTs, Van OMT-2 and Van OMT-3, from the orchid Vanilla planifolia Andrews. These enzymes catalyze the methylation of a single outer hydroxyl group in substrates possessing a 1,2,3-trihydroxybenzene moiety, such as methyl gallate and myricetin. This is a substrate requirement not previously reported for any OMTs. Based on sequence analysis these enzymes are most similar to caffeic acid O-methyltransferases (COMTs), but they have negligible activity with typical COMT substrates. Seven of 12 conserved substrate-binding residues in COMTs are altered in Van OMT-2 and Van OMT-3. Phylogenetic analysis of the sequences suggests that Van OMT-2 and Van OMT-3 evolved from the V. planifolia COMT. These V. planifolia OMTs are new instances of COMT-like enzymes with novel substrate preferences.
authors.affiliation: Department of Plant Biology and Pathology and The Biotechnology Center for Agriculture & the Environment, Cook College, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901, USA.
authors.forename: Huaijun Michael
authors.initials: HM
authors.lastname: Li
authors.forename: David
authors.initials: D
authors.lastname: Rotter
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Hartman
authors.forename: Fulya E
authors.initials: FE
authors.lastname: Pak
authors.forename: Daphna
authors.initials: D
authors.lastname: Havkin-Frenkel
authors.forename: Faith C
authors.initials: FC
authors.lastname: Belanger
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D004926:Escherichia coli / Q000235:genetics; D019143:Evolution, Molecular; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity; D031669:Vanilla / Q000201:enzymology* / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D008780:Methyltransferases; C019608:caffeate O-methyltransferase