Abstract
O-Methyltransferases (OMTs) transfer a methyl group from S-adenosylmethionine to a hydroxyl group of an acceptor. One group of OMTs is the caffeoyl-CoA O-methyltransferase type, which is involved in the biosynthesis of monolignol. In this study, OsOMT26 was cloned from Oryza sativa and the recombinant OsOMT26 protein was characterized. OsOMT26 used not only caffeoyl-CoA as a substrate but also different flavonoids such as luteolin and tricetin. However, when caffeoyl-CoA was used as the substrate, the reactivity of OsOMT26 was approximately 6.6-fold better than when either luteolin or tricetin was used. This result demonstrated that OsOMT26 displayed the typical properties characteristic of CCoAOMT. Molecular modeling followed by site-directed mutagenesis was employed to examine why caffeic acid or caffeoyl-CoA was a better substrate than tricetin. One amino acid, Asp210, turned out to be critical for substrate binding, and site-directed mutagenesis of Asp to Glu improved the enzyme’s reactivity toward tricetin.
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Abbreviations
- CCoAOMT:
-
Caffeoyl-CoA OMT
- COMTs:
-
Caffeic acid OMTs
- 4-CL:
-
4-Coumaroyl-CoA ligase
- OMT:
-
O-methyltransferase
- SAM:
-
S-adenosylmethionine
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Acknowledgments
This work was supported by a grant from Systems and Synthetic Agro-biotech Center through Next-Generation BioGreen 21 Program (PJ007975), Agenda program (NIAS, 8-21-52), Rural Development Administration, Republic of Korea, and also partially by the Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0093824).
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Sung, S.H., Kim, BG., Chong, Y. et al. Characterization of Phenylpropanoid O-Methyltransferase from Rice: Molecular Basis for the Different Reactivity Toward Different Substrates. J. Plant Biol. 54, 314–320 (2011). https://doi.org/10.1007/s12374-011-9169-4
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DOI: https://doi.org/10.1007/s12374-011-9169-4