9B3F

Cryo-EM structure of yeast (Nap1)2-H2A-H2B-Kap114

Summary for 9B3F

• Entry DOI: 10.2210/pdb9b3f/pdb
• Related: 9B23 9B31
• EMDB information: 44136
• Descriptor: NAP1 isoform 1, KAP114 isoform 1, Histone H2A, ... (4 entities in total)
• Functional Keywords: histone, chaperone, import, nucleosome assembly, transport protein
• Biological source: Saccharomyces cerevisiae (brewer's yeast); More
• Total number of polymer chains: 5
• Total formula weight: 214600.70

Authors

Jiou, J.,Fung, H.Y.J.,Chook, Y.M. (deposition date: 2024-03-19, release date: 2024-11-27, Last modification date: 2024-12-11)

Primary citation

Fung, H.Y.J.,Jiou, J.,Niesman, A.B.,Bernardes, N.E.,Chook, Y.M.
Nap1 and Kap114 co-chaperone H2A-H2B and facilitate targeted histone release in the nucleus.
J.Cell Biol., 224:-, 2025

PubMed Abstract: Core histones, synthesized and processed in the cytoplasm, must be chaperoned as they are transported into the nucleus for nucleosome assembly. The importin Kap114 transports H2A-H2B into the yeast nucleus, where RanGTP facilitates histone release. Kap114 and H2A-H2B also bind the histone chaperone Nap1, but how Nap1 and Kap114 cooperate in transport and nucleosome assembly remains unclear. Here, biochemical and structural analyses show that Kap114, H2A-H2B, and a Nap1 dimer (Nap12) associate in the absence and presence of RanGTP to form equimolar complexes. A previous study had shown that RanGTP reduces Kap114's ability to chaperone H2A-H2B, but a new cryo-EM structure of the Nap12•H2A-H2B•Kap114•RanGTP complex explains how both Kap114 and Nap12 interact with H2A-H2B, restoring its chaperoning within the assembly while effectively depositing it into nucleosomes. Together, our results suggest that Kap114 and Nap12 provide a sheltered path that facilitates the transfer of H2A-H2B from Kap114 to Nap12, ultimately directing its specific deposition into nucleosomes.

PubMed: 39601790
DOI: 10.1083/jcb.202408193

Experimental method

ELECTRON MICROSCOPY (3.54 Å)