Structure of the Hir histone chaperone complex.
Mol Cell
; 84(14): 2601-2617.e12, 2024 Jul 25.
Article
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| MEDLINE
| ID: mdl-38925115
ABSTRACT
The evolutionarily conserved HIRA/Hir histone chaperone complex and ASF1a/Asf1 co-chaperone cooperate to deposit histone (H3/H4)2 tetramers on DNA for replication-independent chromatin assembly. The molecular architecture of the HIRA/Hir complex and its mode of histone deposition have remained unknown. Here, we report the cryo-EM structure of the S. cerevisiae Hir complex with Asf1/H3/H4 at 2.9-6.8 Å resolution. We find that the Hir complex forms an arc-shaped dimer with a Hir1/Hir2/Hir3/Hpc2 stoichiometry of 2/4/2/4. The core of the complex containing two Hir1/Hir2/Hir2 trimers and N-terminal segments of Hir3 forms a central cavity containing two copies of Hpc2, with one engaged by Asf1/H3/H4, in a suitable position to accommodate a histone (H3/H4)2 tetramer, while the C-terminal segments of Hir3 harbor nucleic acid binding activity to wrap DNA around the Hpc2-assisted histone tetramer. The structure suggests a model for how the Hir/Asf1 complex promotes the formation of histone tetramers for their subsequent deposition onto DNA.
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Banco de datos:
MEDLINE
Asunto principal:
Unión Proteica
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Saccharomyces cerevisiae
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Histonas
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Proteínas de Ciclo Celular
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Microscopía por Crioelectrón
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Proteínas de Saccharomyces cerevisiae
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Chaperonas de Histonas
Idioma:
En
Año:
2024
Tipo del documento:
Article