| Structural highlights
Function
[CBX7_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. Promotes histone H3 trimethylation at 'Lys-9' (H3K9me3). Binds to trimethylated lysine residues in histones, and possibly also other proteins. Regulator of cellular lifespan by maintaining the repression of CDKN2A, but not by inducing telomerase activity.[1] [2] [3] [4]
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 PubMed
The eight mammalian Cbx proteins are chromodomain-containing proteins involved in regulation of heterochromatin, gene expression, and developmental programs. They are evolutionarily related to the Drosophila HP1 (dHP1) and Pc (dPc) proteins that are key components of chromatin-associated complexes capable of recognizing repressive marks such as trimethylated Lys-9 and Lys-27, respectively, on histone H3. However, the binding specificity and function of the human homologs, Cbx1-8, remain unclear. To this end we employed structural, biophysical, and mutagenic approaches to characterize the molecular determinants of sequence contextual methyllysine binding to human Cbx1-8 proteins. Although all three human HP1 homologs (Cbx1, -3, -5) replicate the structural and binding features of their dHP counterparts, the five Pc homologs (Cbx2, -4, -6, -7, -8) bind with lower affinity to H3K9me3 or H3K27me3 peptides and are unable to distinguish between these two marks. Additionally, peptide permutation arrays revealed a greater sequence tolerance within the Pc family and suggest alternative nonhistone sequences as potential binding targets for this class of chromodomains. Our structures explain the divergence of peptide binding selectivity in the Pc subfamily and highlight previously unrecognized features of the chromodomain that influence binding and specificity.
Recognition and specificity determinants of the human cbx chromodomains.,Kaustov L, Ouyang H, Amaya M, Lemak A, Nady N, Duan S, Wasney GA, Li Z, Vedadi M, Schapira M, Min J, Arrowsmith CH J Biol Chem. 2011 Jan 7;286(1):521-9. Epub 2010 Nov 3. PMID:21047797[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Maertens GN, El Messaoudi-Aubert S, Racek T, Stock JK, Nicholls J, Rodriguez-Niedenfuhr M, Gil J, Peters G. Several distinct polycomb complexes regulate and co-localize on the INK4a tumor suppressor locus. PLoS One. 2009 Jul 28;4(7):e6380. doi: 10.1371/journal.pone.0006380. PMID:19636380 doi:http://dx.doi.org/10.1371/journal.pone.0006380
- ↑ Li Q, Wang X, Lu Z, Zhang B, Guan Z, Liu Z, Zhong Q, Gu L, Zhou J, Zhu B, Ji J, Deng D. Polycomb CBX7 directly controls trimethylation of histone H3 at lysine 9 at the p16 locus. PLoS One. 2010 Oct 29;5(10):e13732. doi: 10.1371/journal.pone.0013732. PMID:21060834 doi:http://dx.doi.org/10.1371/journal.pone.0013732
- ↑ Vandamme J, Volkel P, Rosnoblet C, Le Faou P, Angrand PO. Interaction proteomics analysis of polycomb proteins defines distinct PRC1 complexes in mammalian cells. Mol Cell Proteomics. 2011 Apr;10(4):M110.002642. doi: 10.1074/mcp.M110.002642., Epub 2011 Jan 31. PMID:21282530 doi:10.1074/mcp.M110.002642
- ↑ Kaustov L, Ouyang H, Amaya M, Lemak A, Nady N, Duan S, Wasney GA, Li Z, Vedadi M, Schapira M, Min J, Arrowsmith CH. Recognition and specificity determinants of the human cbx chromodomains. J Biol Chem. 2011 Jan 7;286(1):521-9. Epub 2010 Nov 3. PMID:21047797 doi:10.1074/jbc.M110.191411
- ↑ Kaustov L, Ouyang H, Amaya M, Lemak A, Nady N, Duan S, Wasney GA, Li Z, Vedadi M, Schapira M, Min J, Arrowsmith CH. Recognition and specificity determinants of the human cbx chromodomains. J Biol Chem. 2011 Jan 7;286(1):521-9. Epub 2010 Nov 3. PMID:21047797 doi:10.1074/jbc.M110.191411
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