Max Planck Institute of Biochemistry, Laboratory of Chromatin Biology, Martinsried, Germany
Jacques Bonnet
Max Planck Institute of Biochemistry, Laboratory of Chromatin Biology, Martinsried, Germany
Simon Poepsel
California Institute for Quantitative Biology (QB3), University of California, California Institute for Quantitative Biology (QB3), Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, United States; University of Cologne, Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
Ingmar B Schäfer
Max Planck Institute of Biochemistry, Department of Structural Cell Biology, Martinsried, Germany
Katja Finkl
Max Planck Institute of Biochemistry, Laboratory of Chromatin Biology, Martinsried, Germany
Katharina Schmid
Max Planck Institute of Biochemistry, Laboratory of Chromatin Biology, Martinsried, Germany
Claudia Litz
Max Planck Institute of Biochemistry, Laboratory of Chromatin Biology, Martinsried, Germany
Mike Strauss
Max Planck Institute of Biochemistry, cryoEM Facility, Martinsried, Germany
Christian Benda
Max Planck Institute of Biochemistry, Department of Structural Cell Biology, Martinsried, Germany
Repression of genes by Polycomb requires that PRC2 modifies their chromatin by trimethylating lysine 27 on histone H3 (H3K27me3). At transcriptionally active genes, di- and tri-methylated H3K36 inhibit PRC2. Here, the cryo-EM structure of PRC2 on dinucleosomes reveals how binding of its catalytic subunit EZH2 to nucleosomal DNA orients the H3 N-terminus via an extended network of interactions to place H3K27 into the active site. Unmodified H3K36 occupies a critical position in the EZH2-DNA interface. Mutation of H3K36 to arginine or alanine inhibits H3K27 methylation by PRC2 on nucleosomes in vitro. Accordingly, Drosophila H3K36A and H3K36R mutants show reduced levels of H3K27me3 and defective Polycomb repression of HOX genes. The relay of interactions between EZH2, the nucleosomal DNA and the H3 N-terminus therefore creates the geometry that permits allosteric inhibition of PRC2 by methylated H3K36 in transcriptionally active chromatin.
