Chromodomain-mediated oligomerization of HP1 suggests a nucleosome-bridging mechanism for heterochromatin assembly.
Mol Cell
; 41(1): 67-81, 2011 Jan 07.
Article
em En
| MEDLINE
| ID: mdl-21211724
ABSTRACT
HP1 proteins are central to the assembly and spread of heterochromatin containing histone H3K9 methylation. The chromodomain (CD) of HP1 proteins specifically recognizes the methyl mark on H3 peptides, but the same extent of specificity is not observed within chromatin. The chromoshadow domain of HP1 proteins promotes homodimerization, but this alone cannot explain heterochromatin spread. Using the S. pombe HP1 protein, Swi6, we show that recognition of H3K9-methylated chromatin in vitro relies on an interface between two CDs. This interaction causes Swi6 to tetramerize on a nucleosome, generating two vacant CD sticky ends. On nucleosomal arrays, methyl mark recognition is highly sensitive to internucleosomal distance, suggesting that the CD sticky ends bridge nearby methylated nucleosomes. Strengthening the CD-CD interaction enhances silencing and heterochromatin spread in vivo. Our findings suggest that recognition of methylated nucleosomes and HP1 spread on chromatin are structurally coupled and imply that methylation and nucleosome arrangement synergistically regulate HP1 function.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Cromossômicas não Histona
/
Heterocromatina
/
Nucleossomos
/
Proteínas de Schizosaccharomyces pombe
/
Montagem e Desmontagem da Cromatina
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Mol Cell
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Estados Unidos