EMD-44141

Composite map
Single-particle
2.88 Å
EMD-44141 Deposition: 19/03/2024
Map released: 27/11/2024
Last modified: 11/12/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-44141

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

EMD-44141

Composite map
Single-particle
2.88 Å
EMD-44141 Deposition: 19/03/2024
Map released: 27/11/2024
Last modified: 11/12/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Saccharomyces cerevisiae
Sample: Complex of Kap114 bound to Ran GTPase Gsp1, H2A-H2B and Nap1
Fitted models: 9b3i (Avg. Q-score: 0.293)

Deposition Authors: Fung HYJ , Jiou J , Chook YM
Nap1 and Kap114 co-chaperone H2A-H2B and facilitate targeted histone release in the nucleus.
Fung HYJ , Jiou J , Niesman AB , Bernardes NE , Chook YM
(2025) J Cell Biol , 224
PUBMED: 39601790
DOI: doi:10.1083/jcb.202408193
ISSN: 1540-8140
ASTM: JCLBA3
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.