A catalytic triad – Lys-Asn-Asp – Is essential for the catalysis of the methyl transfer in plant cation-dependent O-methyltransferases
In: Phytochemistry, Jg. 113 (2015-05-01), S. 130-139
Online
unknown
Zugriff:
Crystal structure data of cation-dependent catechol O-methyltransferases (COMTs) from mammals and related caffeoyl coenzyme A OMTs (CCoAOMTs) from plants have suggested operative molecular mechanisms. These include bivalent cations that facilitate deprotonation of vicinal aromatic dihydroxy systems and illustrate a conserved arrangement of hydroxyl and carboxyl ligands consistent with the requirements of a metal-activated catalytic mechanism. The general concept of metal-dependent deprotonation via a complexed aspartate is only one part of a more pronounced proton relay, as shown by semiempirical and DFT quantum mechanical calculations and experimental validations. A previously undetected catalytic triad, consisting of Lys157-Asn181-Asp228 residues is required for complete methyl transfer in case of a cation-dependent phenylpropanoid and flavonoid OMT, as described in this report. This triad appears essential for efficient methyl transfer to catechol-like hydroxyl group in phenolics. The observation is consistent with a catalytic lysine in the case of mammalian COMTs, but jettisons existing assumptions on the initial abstraction of the meta-hydroxyl proton to the metal stabilizing Asp154 (PFOMT) or comparable Asp-carboxyl groups in type of cation-dependent enzymes in plants. The triad is conserved among all characterized plant CCoAOMT-like enzymes, which are required not only for methylation of soluble phenylpropanoids like coumarins or monolignol monomers, but is also present in the similar microbial and mammalian cation-dependent enzymes which methylate a comparable set of substrates.
Titel: |
A catalytic triad – Lys-Asn-Asp – Is essential for the catalysis of the methyl transfer in plant cation-dependent O-methyltransferases
|
---|---|
Autor/in / Beteiligte Person: | Vogt, Thomas ; Manke, Kerstin ; Brandt, Wolfgang |
Link: | |
Zeitschrift: | Phytochemistry, Jg. 113 (2015-05-01), S. 130-139 |
Veröffentlichung: | Elsevier BV, 2015 |
Medientyp: | unknown |
ISSN: | 0031-9422 (print) |
DOI: | 10.1016/j.phytochem.2014.12.018 |
Schlagwort: |
|
Sonstiges: |
|