1pdq
Polycomb chromodomain complexed with the histone H3 tail containing trimethyllysine 27.
Structural highlights
FunctionPC_DROME Polycomb group (PcG) protein. PcG proteins act by forming multiprotein complexes, which are required to maintain the transcriptionally repressive state of homeotic genes throughout development. PcG proteins are not required to initiate repression, but to maintain it during later stages of development. Component of the PcG multiprotein PRC1 complex, a complex that acts via chromatin remodeling and modification of histones; it mediates monoubiquitination of histone H2A 'Lys-118', rendering chromatin heritably changed in its expressibility. Promotes locus-specific chromatin compaction. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedOn the histone H3 tail, Lys 9 and Lys 27 are both methylation sites associated with epigenetic repression, and reside within a highly related sequence motif ARKS. Here we show that the chromodomain proteins Polycomb (Pc) and HP1 (heterochromatin protein 1) are highly discriminatory for binding to these sites in vivo and in vitro. In Drosophila S2 cells, and on polytene chromosomes, methyl-Lys 27 and Pc are both excluded from areas that are enriched in methyl-Lys 9 and HP1. Swapping of the chromodomain regions of Pc and HP1 is sufficient for switching the nuclear localization patterns of these factors, indicating a role for their chromodomains in both target site binding and discrimination. To better understand the molecular basis for the selection of methyl-lysine binding sites, we solved the 1.8 A structure of the Pc chromodomain in complex with a H3 peptide bearing trimethyl-Lys 27, and compared it with our previously determined structure of the HP1 chromodomain in complex with a H3 peptide bearing trimethyl-Lys 9. The Pc chromodomain distinguishes its methylation target on the H3 tail via an extended recognition groove that binds five additional residues preceding the ARKS motif. Molecular basis for the discrimination of repressive methyl-lysine marks in histone H3 by Polycomb and HP1 chromodomains.,Fischle W, Wang Y, Jacobs SA, Kim Y, Allis CD, Khorasanizadeh S Genes Dev. 2003 Aug 1;17(15):1870-81. PMID:12897054[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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