Publications

• Flavonoid 3'-O-methyltransferase from rice: cDNA cloning, characterization and functional expression.

  Kim B.-G., Lee Y., Hur H.-G., Lim Y., Ahn J.-H.

  Plant O-methyltransferases (OMTs) are known to be involved in methylation of plant secondary metabolites, especially phenylpropanoid and flavonoid compounds. An OMT, ROMT-9, was cloned and characterized from rice using a reverse transcriptase polymerase chain reaction (RT-PCR). The blast results f ... >> More

  Plant O-methyltransferases (OMTs) are known to be involved in methylation of plant secondary metabolites, especially phenylpropanoid and flavonoid compounds. An OMT, ROMT-9, was cloned and characterized from rice using a reverse transcriptase polymerase chain reaction (RT-PCR). The blast results for ROMT-9 showed a 73% identity with caffeic acid OMTs from maize and Triticum aestivum. ROMT-9 was expressed in Escherichia coli and its recombinant protein was purified using affinity chromatography. It was then tested for its ability to transfer the methyl group of S-adenosyl-l-methionine to the flavonoid substrates, eriodictyol, luteolin, quercetin, and taxifolin, all of which have a 3'-hydroxyl functional group. The reaction products were analyzed using TLC, HPLC, HPLC/MS, and NMR spectroscopy. The NMR analysis showed that ROMT-9 transferred the methyl group specifically to the 3'-hydroxyl group of quercetin, resulting in the formation of its methoxy derivative. Furthermore, ROMT-9 converted flavonoids containing the 3'-hydroxy functional group such as eriodictyol, luteolin, quercetin and taxifolin into the corresponding methoxy derivatives, suggesting that ROMT-9 is an OMT with strict specificity for the 3'-hydroxy group of flavonoids. << Less

  Phytochemistry 67:387-394(2006) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Use of 3-Deoxy-D-arabino-heptulosonic acid 7-phosphate Synthase (DAHP Synthase) to Enhance the Heterologous Biosynthesis of Diosmetin and Chrysoeriol in an Engineered Strain of <i>Streptomyces albidoflavus</i>.

  Perez-Valero A., Serna-Diestro J., Villar C.J., Lombo F.

  Flavonoids are a large family of polyphenolic compounds with important agro-industrial, nutraceutical, and pharmaceutical applications. Among the structural diversity found in the flavonoid family, methylated flavonoids show interesting characteristics such as greater stability and improved oral b ... >> More

  Flavonoids are a large family of polyphenolic compounds with important agro-industrial, nutraceutical, and pharmaceutical applications. Among the structural diversity found in the flavonoid family, methylated flavonoids show interesting characteristics such as greater stability and improved oral bioavailability. This work is focused on the reconstruction of the entire biosynthetic pathway of the methylated flavones diosmetin and chrysoeriol in <i>Streptomyces albidoflavus</i>. A total of eight different genes (TAL, 4CL, CHS, CHI, FNS1, F3'H/CPR, 3'-OMT, 4'-OMT) are necessary for the heterologous biosynthesis of these two flavonoids, and all of them have been integrated along the chromosome of the bacterial host. The biosynthesis of diosmetin and chrysoeriol has been achieved, reaching titers of 2.44 mg/L and 2.34 mg/L, respectively. Furthermore, an additional compound, putatively identified as luteolin 3',4'-dimethyl ether, was produced in both diosmetin and chrysoeriol-producing strains. With the purpose of increasing flavonoid titers, a 3-Deoxy-D-arabino-heptulosonic acid 7-phosphate synthase (DAHP synthase) from an antibiotic biosynthetic gene cluster (BGC) from <i>Amycolatopsis balhimycina</i> was heterologously expressed in <i>S. albidoflavus</i>, enhancing diosmetin and chrysoeriol production titers of 4.03 mg/L and 3.13 mg/L, which is an increase of 65% and 34%, respectively. To the best of our knowledge, this is the first report on the de novo biosynthesis of diosmetin and chrysoeriol in a heterologous host. << Less

  Int J Mol Sci 25:2776-2776(2024) [PubMed] [EuropePMC]

  This publication is cited by 7 other entries.

• Bio-fermentation of modified flavonoids: an example of in vivo diversification of secondary metabolites.

  Willits M.G., Giovanni M., Prata R.T.N., Kramer C.M., De Luca V., Steffens J.C., Graser G.

  A bio-fermentation technique was used for the in vivo diversification of flavonoid structures based on expression in Escherichia coli of six O-methyltransferases (OMTs) from Mentha x piperita and one O-glucosyltransferase (GT) each from Arabidopsis thaliana and Allium cepa. Enzymes were shown to b ... >> More

  A bio-fermentation technique was used for the in vivo diversification of flavonoid structures based on expression in Escherichia coli of six O-methyltransferases (OMTs) from Mentha x piperita and one O-glucosyltransferase (GT) each from Arabidopsis thaliana and Allium cepa. Enzymes were shown to be regio-specific in in vitro experiments and modified a broad range of flavonoid substrates at various positions. Using the flavonol quercetin as a model substrate, we show that the product spectrum produced with the in vivo approach is identical to that found in vitro. Additionally, using mixed cultures of E. coli expressing different classes of modifying genes (OMTs and GTs), the production of polymethylated flavonoid glucosides was observed. This report demonstrates the potential to increase the structural diversity of plant secondary metabolites using a multi-enzyme, bio-fermentation approach. << Less

  Phytochemistry 65:31-41(2004) [PubMed] [EuropePMC]

  This publication is cited by 23 other entries.

• Purification and properties of an o-dihydricphenol meta-O-methyltransferase from cell suspension cultures of parsley and its relation to flavonoid biosynthesis.

  Ebel J., Hahlbrock K., Grisebach H.

  Biochim Biophys Acta 268:313-326(1972) [PubMed] [EuropePMC]

• Characterization of two cDNA clones which encode O-methyltransferases for the methylation of both flavonoid and phenylpropanoid compounds.

  Gauthier A., Gulick P.J., Ibrahim R.K.

  Enzymatic O-methylation of phenylpropanoid and flavonoid compounds is believed to be catalyzed by distinct classes of O-methyltransferases [EC 2.1.1.6x]. The O-methylated derivatives of phenylpropanoids and flavonoids play an important role in lignification and as antimicrobial compounds, respecti ... >> More

  Enzymatic O-methylation of phenylpropanoid and flavonoid compounds is believed to be catalyzed by distinct classes of O-methyltransferases [EC 2.1.1.6x]. The O-methylated derivatives of phenylpropanoids and flavonoids play an important role in lignification and as antimicrobial compounds, respectively. Two cDNA clones, OMT1 and OMT2, which differ in three amino acid residues were isolated and characterized from the semiaquatic freshwater weed Chrysosplenium americanum (Saxifragaceae). These two novel cDNA clones encode enzymes which catalyze the 3'-O-methylation of the flavonoid aglycones luteolin and quercetin, although they also catalyze the efficient 3/5-O-methylation of the phenylpropanoids caffeic and 5-hydroxyferulic acids, respectively. Both recombinant proteins were partially purified from an Escherichia coli expression system and their kinetic parameters were compared using two flavonoids and two phenylpropanoids as substrates. Although both gene products methylate caffeic acid and 5-hydroxyferulic acid to a similar extent, they exhibit a threefold higher affinity for and a four-to sixfold increase in turnover of flavonoid compounds. The gene product of OMT1 accepts the flavonoid substrates luteolin and quercetin for methylation at a higher rate than that of OMT2, as indicated by a two-to threefold increase in its Vmax values and turnover ratios. The fact that C. americanum accumulates a variety of highly methylated flavonols and exhibits little lignification suggests that these two flavonoid OMT clones have retained their ability to O-methylate phenylpropanoids as well. These results are discussed in relation to differences in the amino acid sequences of these two clones, as well as with other O-methyltransferases, and the evolutionary divergence of these genes in plants. << Less

  Arch. Biochem. Biophys. 351:243-249(1998) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.