title: Molecular and biochemical characterization of a benzenoid/phenylpropanoid meta/para-O-methyltransferase from Rauwolfia serpentina roots.
abstract: The monoterpenoid indole alkaloids, reserpine and rescinnamine contain 3, 4, 5-trimethoxybenzoate or 3, 4, 5-trimethoxycinnamate, respectively, within their structures and they accumulate in different plant organs and particularly within roots of Rauwolfia serpentina. This plant also accumulates acylated sugars substituted with 3, 4, 5-trimethoxybenzoate and 3, 4, 5-trimethoxycinnamate. In the present study, transcriptome and metabolome analyses of R. serpentina roots allowed the identification of 7 candidate O-methytransferase (OMT) genes that might be associated with the formation of 3, 4, 5-trimethoxybenzoate and 3, 4, 5-trimethoxycinnamate and led to the molecular cloning of 4 genes for functional expression and analysis. Two candidate genes were expressed in E. coli and were shown to use different phenolics as methyl acceptors. RsOMT1, a member of the caffeoyl CoA-OMT-like family of genes, converted 3, 5 dimethoxy-4-hydroxycinnamic, caffeic and 3, 4, 5 trihydroxybenzoic acids to trimethoxycinnamic-, ferulic/isoferulic- and 3-methoxy, 4, 5 dihydroxybenzoic or 4-methoxy, 3, 5 dihydroxybenzoic acids, respectively, when supplied with these substrates. RsOMT3, a member of the caffeic acid-OMT-like family of genes, only converted caffeic acid to ferulic acid. Both enzymes showed considerable promiscuity with respect to various flavonoid substrates that they accepted. The para-O-methylation activity of RsOMT1 is quite rare and unusual for plant OMTs. The involvement of RsOMT1 and RsOMT3 in the assembly of trimethoxybenzoic and trimethoxycinnamic acids is discussed.
authors: Department of Biological Sciences, 1812 Sir Isaac Brock Way, Brock University, St. Catharines, Ontario L2S 3A1, Canada. Electronic address: bw09ep@badger.ac.brocku.ca.
authors: Brent
authors: B
authors: Wiens
authors: Department of Biological Sciences, 1812 Sir Isaac Brock Way, Brock University, St. Catharines, Ontario L2S 3A1, Canada. Electronic address: vdeluca@brocku.ca.
authors: Vincenzo
authors: V
authors: De Luca
mesh_terms: D000214:Acyl Coenzyme A; D001565:Benzoates / Q000378:metabolism; D002934:Cinnamates / Q000378:metabolism; D003001:Cloning, Molecular; D003373:Coumaric Acids / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005419:Flavonoids / Q000378:metabolism; D008780:Methyltransferases / Q000378:metabolism*; D015394:Molecular Structure; D018517:Plant Roots / Q000737:chemistry / Q000201:enzymology; D011926:Rauwolfia / Q000201:enzymology* / Q000235:genetics; D012110:Reserpine / Q000031:analogs & derivatives / Q000378:metabolism; D046948:Secologanin Tryptamine Alkaloids / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D000214:Acyl Coenzyme A; D001565:Benzoates; D002934:Cinnamates; D003373:Coumaric Acids; D005419:Flavonoids; D046948:Secologanin Tryptamine Alkaloids; C058645:caffeoyl-coenzyme A; D012110:Reserpine; C004999:ferulic acid; D008780:Methyltransferases; C046455:reserpic acid; C084826:rescinnamine
keywords: Rauwolfia serpentina; Reserpine and rescinamine assembly; Trimethoxybenzoic-and trimethoxycinnamic acid biosynthesis