8pp7
human RYBP-PRC1 bound to mononucleosome
Structural highlights
FunctionBMI1_HUMAN Component of a Polycomb group (PcG) multiprotein PRC1-like complex, a complex class required to maintain the transcriptionally repressive state of many genes, including Hox genes, throughout development. PcG PRC1 complex acts via chromatin remodeling and modification of histones; it mediates monoubiquitination of histone H2A 'Lys-119', rendering chromatin heritably changed in its expressibility. In the PRC1 complex, it is required to stimulate the E3 ubiquitin-protein ligase activity of RNF2/RING2.[1] [2] [3] Publication Abstract from PubMedHistone H2A monoubiquitination (H2Aub1) by the PRC1 subunit RING1B entails a positive feedback loop, mediated by the RING1B-interacting protein RYBP. We uncover that human RYBP-PRC1 binds unmodified nucleosomes via RING1B but H2Aub1-modified nucleosomes via RYBP. RYBP interactions with both ubiquitin and the nucleosome acidic patch create the high binding affinity that favors RYBP- over RING1B-directed PRC1 binding to H2Aub1-modified nucleosomes; this enables RING1B to monoubiquitinate H2A in neighboring unmodified nucleosomes. Structural basis of the histone ubiquitination read-write mechanism of RYBP-PRC1.,Ciapponi M, Karlukova E, Schkolziger S, Benda C, Muller J Nat Struct Mol Biol. 2024 Jul;31(7):1023-1027. doi: 10.1038/s41594-024-01258-x. , Epub 2024 Mar 25. PMID:38528151[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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