title: Cation dependent O-methyltransferases from rice.
abstract: Two lower molecular mass OMT genes (ROMT-15 and -17) were cloned from rice and expressed in Escherichia coli as glutathione S-transferase fusion proteins. ROMT-15 and -17 metabolized caffeoyl-CoA, flavones and flavonols containing two vicinal hydroxyl groups, although they exhibited different substrate specificities. The position of methylation in both luteolin and quercetin was determined to be the 3' hydroxyl group and myricetin and tricetin were methylated not only at 3' but also at 5' hydroxyl groups. ROMT-15 and -17 are cation-dependent and mutation of the predicted metal binding sites resulted in the loss of the enzyme activity, indicating that the metal ion has a critical role in the enzymatic methylation.
authors.affiliation: Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, South Korea.
authors.forename: Yoon Jung
authors.initials: YJ
authors.lastname: Lee
authors.forename: Bong Gyu
authors.initials: BG
authors.lastname: Kim
authors.forename: Youhoon
authors.initials: Y
authors.lastname: Chong
authors.forename: Yoongho
authors.initials: Y
authors.lastname: Lim
authors.forename: Joong-Hoon
authors.initials: JH
authors.lastname: Ahn
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism*; D001665:Binding Sites; D002384:Catalysis; D002412:Cations / Q000378:metabolism*; D005419:Flavonoids / Q000378:metabolism*; D015870:Gene Expression; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008970:Molecular Weight; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D000214:Acyl Coenzyme A; D002412:Cations; D005419:Flavonoids; C058645:caffeoyl-coenzyme A; D008780:Methyltransferases; C059825:caffeoyl-CoA O-methyltransferase