Excision of 5-hydroxymethylcytosine by DEMETER family DNA glycosylases

Biochem Biophys Res Commun. 2014 Apr 18;446(4):1067-72. doi: 10.1016/j.bbrc.2014.03.060. Epub 2014 Mar 21.


In plants and animals, 5-methylcytosine (5mC) serves as an epigenetic mark to repress gene expression, playing critical roles for cellular differentiation and transposon silencing. Mammals also have 5-hydroxymethylcytosine (5hmC), resulting from hydroxylation of 5mC by TET family-enzymes. 5hmC is abundant in mouse Purkinje neurons and embryonic stem cells, and regarded as an important intermediate for active DNA demethylation in mammals. However, the presence of 5hmC in plants has not been clearly demonstrated. In Arabidopsis, the DEMETER (DME) family DNA glycosylases efficiently remove 5mC, which results in DNA demethylation and transcriptional activation of target genes. Here we show that DME and ROS1 have a significant 5hmC excision activity in vitro, although we detected no 5hmC in Arabidopsis, suggesting that it is very unlikely for plants to utilize 5hmC as a DNA demethylation intermediate. Our results indicate that both plants and animals have 5mC in common but DNA demethylation systems have independently evolved with distinct mechanisms.

Keywords: 5-Hydroxymethylcytosine; 5-Methylcytosine; DEMETER; DNA demethylation; DNA glycosylase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-Methylcytosine / metabolism
  • Animals
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism*
  • Cytosine / analogs & derivatives*
  • Cytosine / metabolism
  • DNA Glycosylases / metabolism*
  • DNA Methylation
  • Mice
  • N-Glycosyl Hydrolases / metabolism*
  • Nuclear Proteins / metabolism*
  • Signal Transduction
  • Trans-Activators / metabolism*


  • Arabidopsis Proteins
  • Nuclear Proteins
  • ROS1 protein, Arabidopsis
  • Trans-Activators
  • 5-hydroxymethylcytosine
  • 5-Methylcytosine
  • Cytosine
  • DEMETER protein, Arabidopsis
  • DNA Glycosylases
  • N-Glycosyl Hydrolases