Structural highlights
Function
CBX3_HUMAN Seems to be involved in transcriptional silencing in heterochromatin-like complexes. Recognizes and binds histone H3 tails methylated at 'Lys-9', leading to epigenetic repression. May contribute to the association of the heterochromatin with the inner nuclear membrane through its interaction with lamin B receptor (LBR). Involved in the formation of functional kinetochore through interaction with MIS12 complex proteins.
Publication Abstract from PubMed
BACKGROUND: HP1 proteins are highly conserved heterochromatin proteins, which have been identified to be structural adapters assembling a variety of macromolecular complexes involved in regulation of gene expression, chromatin remodeling and heterochromatin formation. Much evidence shows that HP1 proteins interact with numerous proteins including methylated histones, histone methyltransferases and so on. Cbx3 is one of the paralogues of HP1 proteins, which has been reported to specifically recognize trimethylated histone H3K9 mark, and a consensus binding motif has been defined for the Cbx3 chromodomain. METHODOLOGY/PRINCIPAL FINDINGS: Here, we found that the Cbx3 chromodomain can bind to H1K26me2 and G9aK185me3 with comparable binding affinities compared to H3K9me3. We also determined the crystal structures of the human Cbx3 chromodomain in complex with dimethylated histone H1K26 and trimethylated G9aK185 peptides, respectively. The complex structures unveil that the Cbx3 chromodomain specifically bind methylated histone H1K26 and G9aK185 through a conserved mechanism. CONCLUSIONS/SIGNIFICANCE: The Cbx3 chromodomain binds with comparable affinities to all of the methylated H3K9, H1K26 and G9aK185 peptides. It is suggested that Cbx3 may regulate gene expression via recognizing both histones and non-histone proteins.
Structural basis of the chromodomain of Cbx3 bound to methylated peptides from histone h1 and G9a.,Ruan J, Ouyang H, Amaya MF, Ravichandran M, Loppnau P, Min J, Zang J PLoS One. 2012;7(4):e35376. doi: 10.1371/journal.pone.0035376. Epub 2012 Apr 13. PMID:22514736[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Ruan J, Ouyang H, Amaya MF, Ravichandran M, Loppnau P, Min J, Zang J. Structural basis of the chromodomain of Cbx3 bound to methylated peptides from histone h1 and G9a. PLoS One. 2012;7(4):e35376. doi: 10.1371/journal.pone.0035376. Epub 2012 Apr 13. PMID:22514736 doi:http://dx.doi.org/10.1371/journal.pone.0035376
