8GIX

Chaetomium thermophilum Hir3

Summary for 8GIX

• Entry DOI: 10.2210/pdb8gix/pdb
• EMDB information: 40078
• Descriptor: Histone transcription regulator 3 homolog, 3,3',3''-phosphanetriyltripropanoic acid (2 entities in total)
• Functional Keywords: histone, complex, subunit, chaperone
• Biological source: Thermochaetoides thermophila DSM 1495
• Total number of polymer chains: 2
• Total formula weight: 501576.72

Authors

Szurgot, M.R.,van Eeuwen, T.,Kim, H.J.,Marmorstein, R. (deposition date: 2023-03-14, release date: 2024-07-10, Last modification date: 2024-08-07)

Primary citation

Kim, H.J.,Szurgot, M.R.,van Eeuwen, T.,Ricketts, M.D.,Basnet, P.,Zhang, A.L.,Vogt, A.,Sharmin, S.,Kaplan, C.D.,Garcia, B.A.,Marmorstein, R.,Murakami, K.
Structure of the Hir histone chaperone complex.
Mol.Cell, 84:2601-2617.e12, 2024

PubMed Abstract: The evolutionarily conserved HIRA/Hir histone chaperone complex and ASF1a/Asf1 co-chaperone cooperate to deposit histone (H3/H4) 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) 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.

PubMed: 38925115
DOI: 10.1016/j.molcel.2024.05.031

Experimental method

ELECTRON MICROSCOPY (3.9 Å)