Evolution of novel O-methyltransferases from the Vanilla planifolia caffeic acid O-methyltransferase

Huaijun Michael Li, David Rotter, Thomas G. Hartman, Fulya E. Pak, Daphna Havkin-Frenkel, Faith C. Belanger

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The biosynthesis of many plant secondary compounds involves the methylation of one or more hydroxyl groups, catalyzed by O-methyltransferases (OMTs). Here, we report the characterization of two OMTs, Van OMT-2 and Van OMT-3, from the orchid Vanilla planifolia Andrews. These enzymes catalyze the methylation of a single outer hydroxyl group in substrates possessing a 1,2,3-trihydroxybenzene moiety, such as methyl gallate and myricetin. This is a substrate requirement not previously reported for any OMTs. Based on sequence analysis these enzymes are most similar to caffeic acid O-methyltransferases (COMTs), but they have negligible activity with typical COMT substrates. Seven of 12 conserved substrate-binding residues in COMTs are altered in Van OMT-2 and Van OMT-3. Phylogenetic analysis of the sequences suggests that Van OMT-2 and Van OMT-3 evolved from the V. planifolia COMT. These V. planifolia OMTs are new instances of COMT-like enzymes with novel substrate preferences.

Original languageEnglish (US)
Pages (from-to)537-552
Number of pages16
JournalPlant Molecular Biology
Issue number3
StatePublished - Jun 2006

All Science Journal Classification (ASJC) codes

  • Agronomy and Crop Science
  • Genetics
  • Plant Science


  • O-methyltransferase
  • Secondary metabolites
  • Vanilla


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