Molecular analysis of PRC2 recruitment to DNA in chromatin and its inhibition by RNA.

TitleMolecular analysis of PRC2 recruitment to DNA in chromatin and its inhibition by RNA.
Publication TypeJournal Article
Year of Publication2017
AuthorsWang, X, Paucek, RD, Gooding, AR, Brown, ZZ, Ge, EJ, Muir, TW, Cech, TR
JournalNat Struct Mol Biol
Date Published2017 Dec
KeywordsBase Composition, Cell Line, Chromatin, DNA, DNA Methylation, DNA-Binding Proteins, Epigenesis, Genetic, Gene Silencing, Histones, Humans, Nucleosomes, Polycomb Repressive Complex 2, Protein Binding, Repressor Proteins, RNA

<p>Many studies have revealed pathways of epigenetic gene silencing by Polycomb repressive complex 2 (PRC2) in vivo, but understanding the underlying molecular mechanisms requires biochemistry. Here we analyze interactions of reconstituted human PRC2 with nucleosome complexes. Histone modifications, the H3K27M cancer mutation, and inclusion of JARID2 or EZH1 in the PRC2 complex have unexpectedly minor effects on PRC2-nucleosome binding. Instead, protein-free linker DNA dominates the PRC2-nucleosome interaction. Specificity for CG-rich sequences is consistent with PRC2 occupying CG-rich DNA in vivo. PRC2 preferentially binds methylated DNA regulated by its AEBP2 subunit, suggesting how DNA and histone methylation collaborate to repress chromatin. We find that RNA, known to inhibit PRC2 activity, is not a methyltransferase inhibitor per se. Instead, RNA sequesters PRC2 from nucleosome substrates, because PRC2 binding requires linker DNA, and RNA and DNA binding are mutually exclusive. Together, we provide a model for PRC2 recruitment and an explanation for how actively transcribed genomic regions bind PRC2 but escape silencing.</p>

Alternate JournalNat Struct Mol Biol
PubMed ID29058709
PubMed Central IDPMC5771497
Grant List / HHMI / Howard Hughes Medical Institute / United States
P01 CA196539 / CA / NCI NIH HHS / United States
R01 GM086868 / GM / NIGMS NIH HHS / United States
R37 GM086868 / GM / NIGMS NIH HHS / United States