title: Molecular cloning of an O-methyltransferase from adventitious roots of Carapichea ipecacuanha.
abstract: Carapichea ipecacuanha produces various emetine-type alkaloids, known as ipecac alkaloids, which have long been used as expectorants, emetics, and amebicides. In this study, we isolated an O-methyltransferase cDNA from this medicinal plant. The encoded protein (CiOMT1) showed 98% sequence identity to IpeOMT2, which catalyzes the 7'-O-methylation of 7'-O-demethylcephaeline to form cephaeline at the penultimate step of emetine biosynthesis (Nomura and Kutchan, J. Biol. Chem., 285, 7722-7738 (2010)). Recombinant CiOMT1 showed both 7'-O-methylation and 6'-O-methylation activities at the last two steps of emetine biosynthesis. This indicates that small differences in amino acid residues are responsible for distinct regional methylation specificities between IpeOMT2 and CiOMT1, and that CiOMT1 might contribute to two sequential O-methylation steps from 7'-O-demethylcephaeline to emetine.
authors.affiliation: Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Bo Eng
authors.initials: BE
authors.lastname: Cheong
authors.forename: Tomoya
authors.initials: T
authors.lastname: Takemura
authors.forename: Kayo
authors.initials: K
authors.lastname: Yoshimatsu
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
mesh_terms: D000470:Alkaloids / Q000096:biosynthesis; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D019143:Evolution, Molecular; D008780:Methyltransferases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D018517:Plant Roots / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D019666:Rubiaceae / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D000470:Alkaloids; D018076:DNA, Complementary; D011994:Recombinant Proteins; D008780:Methyltransferases