Maintenance DNA methyltransferase (Met1) and silencing of CpG-methylated foreign DNA in Volvox carteri

P. Babinger, R. Völkl, I. Cakstina, A. Maftei, R. Schmitt

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


DNA methylation plays an important role in the gene-silencing network of higher eukaryotes. We have analyzed the 21.5-kb maintenance methyltransferase (M-MTase) gene, met1, of the multicellular green alga Volvox carteri. The met1 transcript was detected only during the period when DNA replication and cell division are taking place. It encodes a 238 kDa protein containing eight C-terminal activity domains typical of M-MTases, plus upstream DNA-binding domains including the ProDom domain PD003757, which experimental analyses in animal systems have indicated is required for targeting the enzyme to DNA-replication foci. Several insertions of unknown function make Volvox Met1 the largest known member of the Met1/Dnmt1 family. Here we also show that several endogenous transposon families are CpG-methyated in Volvox, which we think causes them to be inactive. This view is supported by the observation that an in vitro CpG-methylated gene introduced into Volvox was maintained in the methylated and silent state over >100 generations. Thus, we believe that Met1 recognizes and perpetuates the in vitro methylation signal, and that the silencing machinery is then able to transduce such a methylation-only signal into a stable heterochromatic (and silent) state.

Original languageEnglish
Pages (from-to)325-336
Number of pages12
JournalPlant Molecular Biology
Issue number3
Publication statusPublished - Feb 2007
Externally publishedYes


  • Bisulfite genomic sequencing
  • CpG methylation
  • DNA methyltransferase
  • Transgene silencing
  • Transposon silencing
  • Volvox carteri

Field of Science*

  • 1.6 Biological sciences

Publication Type*

  • 1.1. Scientific article indexed in Web of Science and/or Scopus database


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