Untitled

Ibrahim, Ragai K.; Bruneau, Anne; Bantignies, Brigitte

doi:10.1023/a:1005939803300

Cited by 247 publications

(80 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2A), functionally important residues are conserved and provide anchoring points for the alignment process. Along the OMT sequences, several conserved amino acid stretches have been previously detected and proposed as characteristic OMT signatures (8,9,11,38). Finally, it is worth noting that two internal regions and the N-terminal extension of CCoAOMTs are absent in rat CatOMT ( Fig.…”

Section: Resultsmentioning

confidence: 87%

Identification of the Enzymatic Active Site of Tobacco Caffeoyl-coenzyme A O-Methyltransferase by Site-directed Mutagenesis

Hoffmann

Maury

Bergdoll

et al. 2001

Journal of Biological Chemistry

View full text Add to dashboard Cite

Animal catechol O-methyltransferases and plant caffeoyl-coenzyme A O-methyltransferases share about 20% sequence identity and display common structural features. The crystallographic structure of rat liver catechol O-methyltransferase was used as a template to construct a homology model for tobacco caffeoyl-coenzyme A Omethyltransferase. Integrating substrate specificity data, the three-dimensional model identified several amino acid residues putatively involved in substrate binding. These residues were mutated by a polymerase chain reaction method and wild-type and mutant enzymes were each expressed in Escherichia coli and purified. Substitution of Arg-220 with Thr resulted in the total loss of enzyme activity, thus indicating that Arg-220 is involved in the electrostatic interaction with the coenzyme A moiety of the substrate. Changes of Asp-58 to Ala and Gln-61 to Ser were shown to increase K m values for caffeoyl coenzyme A and to decrease catalytic activity. Deletions of two amino acid sequences specific for plant enzymes abolished activity. The secondary structures of the mutants, as measured by circular dichroism, were essentially unperturbed as compared with the wild type. Similar changes in circular dichroism spectra were observed after addition of caffeoyl coenzyme A to the wild-type enzyme and the substitution mutants but not in the case of deletion mutants, thus revealing the importance of these sequences in substrate-enzyme interactions.

show abstract

Section: Resultsmentioning

confidence: 87%

Identification of the Enzymatic Active Site of Tobacco Caffeoyl-coenzyme A O-Methyltransferase by Site-directed Mutagenesis

Hoffmann

Maury

Bergdoll

et al. 2001

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Among the many different gene functions contributing to this plasticity are those that correspond to modifying enzymes such as the multigene families encoding P450 hydroxylases (6), methyltransferases (7), and the glycosyltransferases (8). Typically in plants, the group of glycosyltransferases (UDP-glucosyltransferase; UGTs) 1 involved in these modifications are characterized by the presence of a signature motif located toward the C terminus of the polypeptide (9, 10).…”

mentioning

confidence: 99%

Identification of Glucosyltransferase Genes Involved in Sinapate Metabolism and Lignin Synthesis in Arabidopsis

Lim

Parr

et al. 2001

Journal of Biological Chemistry

195

161

View full text Add to dashboard Cite

Sinapic acid is a major phenylpropanoid in Brassicaceae providing intermediates in two distinct metabolic pathways leading to sinapoyl esters and lignin synthesis. Glucosyltransferases play key roles in the formation of these intermediates, either through the production of the high energy compound 1-O-sinapoylglucose leading to sinapoylmalate and sinapoylcholine or through the production of sinapyl alcohol-4-O-glucoside, potentially leading to the syringyl units found in lignins. While the importance of these glucosyltransferases has been recognized for more than 20 years, their corresponding genes have not been identified. Combining sequence information in the Arabidopsis genomic data base with biochemical data from screening the activity of recombinant proteins in vitro, we have now identified five gene sequences encoding enzymes that can glucosylate sinapic acid, sinapyl alcohol, and their related phenylpropanoids. The data provide a foundation for future understanding and manipulation of sinapate metabolism and lignin biology in Arabidopsis.

show abstract

“…The active sites of SAM-dependent methyltransferases, especially the SAM binding site, are highly conserved. 34,35 As shown in Figure 2, the SAM binding site was composed of conserved residues and the substrate binding site was lined by mostly hydrophobic residues. Comparative substrate binding site analysis of IOMT and HOMT showed various differences in the respective substrate binding residues.…”

Section: Resultsmentioning

confidence: 99%

Molecular Modeling and Docking Studies of 3'-Hydroxy-N-methylcoclaurine 4'-O-Methyltransferase from Coptis chinensis

Zhu¹,

Zhu²,

Fan³

et al. 2014

Bulletin of the Korean Chemical Society

View full text Add to dashboard Cite

Coptis chinensis 3'-hydroxy-N-methylcoclaurine 4'-O-methyltransferase (HOMT), an essential enzyme in the berberine biosynthetic pathway, catalyzes the methylation of 3'-hydroxy-N-methylcoclaurine (HMC) producing reticuline. A 3D model of HOMT was constructed by homology modeling and further subjected to docking with its ligands and molecular dynamics simulations. The 3D structure of HOMT revealed unique structural features which permitted the methylation of HMC. The methylation of HMC was proposed to proceed by deprotonation of the 4'-hydroxyl group via His257 and Asp258 of HOMT, followed by a nucleophilic attack on the SAM-methyl group resulting in reticuline. HOMT showed high substrate specificity for methylation of HMC. The study evidenced that Gly117, Thr312 and Asp258 in HOMT might be the key residues for orienting substrate for specific catalysis.

show abstract

Untitled

Cited by 247 publications

References 67 publications

Identification of the Enzymatic Active Site of Tobacco Caffeoyl-coenzyme A O-Methyltransferase by Site-directed Mutagenesis

Identification of the Enzymatic Active Site of Tobacco Caffeoyl-coenzyme A O-Methyltransferase by Site-directed Mutagenesis

Identification of Glucosyltransferase Genes Involved in Sinapate Metabolism and Lignin Synthesis in Arabidopsis

Molecular Modeling and Docking Studies of 3'-Hydroxy-N-methylcoclaurine 4'-O-Methyltransferase from Coptis chinensis

Contact Info

Product

Resources

About