title: Substrate preferences of the EZH2 histone methyltransferase complex.
abstract: Histone methylation plays an important role in chromatin dynamics and gene expression. Methylation of histone H3-lysine 27 by the EZH2 complex has been linked to the silencing of homeotic genes and the inactivation of the X chromosome. Here we report a characterization of the substrate preferences of the enzyme complex using a reconstituted chromatin and enzyme system. We found that the linker histone H1, when incorporated into nucleosomes, stimulates the enzymatic activity toward histone H3. This stimulatory activity may be explained by protein-protein interactions between H1 and components of the EZH2 complex. In addition, we found that the EZH2 complex exhibits a dramatic preference for dinucleosomes when compared with mononucleosomes and that the stimulation of H3 methylation by H1 requires dinucleosomes or oligonucleosome substrates. Furthermore, in contrast with a recent study suggesting that Embryonic Ectoderm Development EED isoforms may affect substrate specificity, we found that EZH2 complexes reconstituted with different EED isoforms exhibit similar substrate preference and specificity. Our work supports the hypothesis that linker histone H1 and chromatin structure are important factors in determining the substrate preference of the EZH2 histone methyltransferase complex.
authors.affiliation: Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, North Carolina 27599, USA.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Martin
authors.forename: Ru
authors.initials: R
authors.lastname: Cao
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D016367:Baculoviridae / Q000235:genetics; D002843:Chromatin / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004587:Electrophoresis, Agar Gel; D000071221:Enhancer of Zeste Homolog 2 Protein; D005801:Genes, Homeobox; D005982:Glutathione Transferase / Q000378:metabolism; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000032:analysis / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008745:Methylation; D009707:Nucleosomes / Q000378:metabolism; D063151:Polycomb Repressive Complex 2; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011496:Protein Methyltransferases; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013379:Substrate Specificity; D013462:Sulfur Radioisotopes; D014157:Transcription Factors / Q000378:metabolism*; D049951:X Chromosome Inactivation
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D006657:Histones; D009707:Nucleosomes; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D013462:Sulfur Radioisotopes; D014157:Transcription Factors; D008715:Methionine; D000076983:Histone Methyltransferases; D011496:Protein Methyltransferases; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D011495:Histone-Lysine N-Methyltransferase; D063151:Polycomb Repressive Complex 2; D005982:Glutathione Transferase; D008239:Lysine