title: Peptide recognition by heterochromatin protein 1 (HP1) chromoshadow domains revisited: Plasticity in the pseudosymmetric histone binding site of human HP1.
abstract: Heterochromatin protein 1 (HP1), a highly conserved non-histone chromosomal protein in eukaryotes, plays important roles in the regulation of gene transcription. Each of the three human homologs of HP1 includes a chromoshadow domain (CSD). The CSD interacts with various proteins bearing the PXVXL motif but also with a region of histone H3 that bears the similar PXXVXL motif. The latter interaction has not yet been resolved in atomic detail. Here we demonstrate that the CSDs of all three human HP1 homologs have comparable affinities to the PXXVXL motif of histone H3. The HP1 C-terminal extension enhances the affinity, as does the increasing length of the H3 peptide. The crystal structure of the human HP1γ CSD (CSDγ) in complex with an H3 peptide suggests that recognition of H3 by CSDγto some extent resembles CSD-PXVXL interaction. Nevertheless, the prolyl residue of the PXXVXL motif appears to play a role distinct from that of Pro in the known HP1β CSD-PXVXL complexes. We consequently generalize the historical CSD-PXVXL interaction model and expand the search scope for additional CSD binding partners.
authors.affiliation: From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Liu
authors.affiliation: From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and.
authors.forename: Su
authors.initials: S
authors.lastname: Qin
authors.affiliation: From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and.
authors.forename: Ming
authors.initials: M
authors.lastname: Lei
authors.affiliation: From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Tempel
authors.affiliation: From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and.
authors.forename: Yuzhe
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and.
authors.forename: Peter
authors.initials: P
authors.lastname: Loppnau
authors.affiliation: From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Li
authors.affiliation: From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and jr.min@utoronto.ca.|the Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
authors.forename: Jinrong
authors.initials: J
authors.lastname: Min
mesh_terms: D020816:Amino Acid Motifs; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D006801:Humans; D000072417:Protein Domains
chemical_list: C000715593:CBX1 protein, human; D002868:Chromosomal Proteins, Non-Histone; D000090266:Chromobox Protein Homolog 5
keywords: chromatin regulation; chromatin structure; heterochromatin; histone; peptide interaction