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Article

  • The EMBO Journal (2005) 24, 2783 - 2791
  • doi:10.1038/sj.emboj.7600743

Published online: 7 July 2005

Distinct regulation of histone H3 methylation at lysines 27 and 9 by CpG methylation in Arabidopsis

Olivier Mathieu1,2, Aline V Probst1,2,3 and Jerzy Paszkowski1

  1. Laboratory of Plant Genetics, University of Geneva, Geneva, Switzerland
  2. These authors contributed equally to this work
  3. Present address: Laboratory of Nuclear Dynamics and Genome Plasticity, UMR 218 CNRS/Institute Curie, 26 rue d'Ulm, 75248 Paris Cedex 5, France

Correspondence to:

Olivier Mathieu, Laboratory of Plant Genetics, University of Geneva, Sciences III, 30 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland. Tel.: +41 22 379 3026; Fax: +41 22 379 3107; E-mail: olivier.mathieu@bioveg.unige.ch

Received 6 April 2005; Accepted 15 June 2005

Transcriptional activity and structure of chromatin are correlated with patterns of covalent DNA and histone modification. Previous studies have revealed that high levels of histone H3 dimethylation at lysine 9 (H3K9me2), characteristic of transcriptionally silent heterochromatin in Arabidopsis, require hypermethylation of DNA at CpG sites. Here, we report that CpG hypermethylation characteristic of heterochromatin specifically prevented H3K27 trimethylation (H3K27me3). H3K27 mono- and dimethylation mark silent heterochromatin independently of DNA methylation. Upon loss of CpG methylation, there was target-specific enrichment of H3K27me3 in heterochromatin that correlated with transcriptional reactivation. Moreover, using the kyp mutant affected in H3K9me2, we showed that changes in H3K27me3 occurred independently of the levels of H3K9me2. Therefore, CpG methylation provides distinct and direct information for a specific subset of histone methylation marks. The observed independence of the regulation of H3K9 and H3K27 methylation by CpG methylation refines the recently proposed combinatorial histone code involving these two marks.

  • Keywords:

    • CpG methylation,
    • histone H3 lysine 27,
    • histone code,
    • silent chromatin