+
Open data
-
Basic information
Entry | Database: PDB / ID: 9b23 | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Title | Cryo-EM structure of Nap1 core | ||||||||||||||||||
![]() | NAP1 isoform 1 | ||||||||||||||||||
![]() | CHAPERONE / Histone | ||||||||||||||||||
Function / homology | : ![]() | ||||||||||||||||||
Biological species | ![]() ![]() | ||||||||||||||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.2 Å | ||||||||||||||||||
![]() | Jiou, J. / Fung, H.Y.J. / Chook, Y.M. | ||||||||||||||||||
Funding support | ![]()
| ||||||||||||||||||
![]() | ![]() Title: Nap1 and Kap114 co-chaperone H2A-H2B and facilitate targeted histone release in the nucleus. Authors: Ho Yee Joyce Fung / Jenny Jiou / Ashley B Niesman / Natalia E Bernardes / Yuh Min Chook / ![]() 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 ...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. #1: Journal: bioRxiv / Year: 2024 Title: Nap1 and Kap114 co-chaperone H2A-H2B and facilitate targeted histone release in the nucleus. Authors: Ho Yee Joyce Fung / Ashley B Neisman / Natalia E Bernardes / Jenny Jiou / Yuh Min Chook Abstract: Core histones are synthesized and processed in the cytoplasm before transport into the nucleus for assembly into nucleosomes; however, they must also be chaperoned as free histones are toxic. The ...Core histones are synthesized and processed in the cytoplasm before transport into the nucleus for assembly into nucleosomes; however, they must also be chaperoned as free histones are toxic. The importin Kap114 binds and transports histone H2A-H2B into the yeast nucleus, where RanGTP facilitates H2A-H2B release. Kap114 and H2A-H2B also bind the Nap1 histone chaperone, which is found in both the cytoplasm and the nucleus, but how Nap1 and Kap114 cooperate in H2A-H2B processing and nucleosome assembly has been unclear. To understand these mechanisms, we used biochemical and structural analyses to reveal how Nap1, Kap114, H2A-H2B and RanGTP interact. We show that Kap114, H2A-H2B and a Nap1 dimer (Nap1 ) assemble into a 1:1:1 ternary complex. Cryogenic electron microscopy revealed two distinct Kap114/Nap1 /H2A-H2B structures: one of H2A-H2B sandwiched between Nap1 and Kap114, and another in which Nap1 bound to the Kap114·H2A-H2B complex without contacting H2A-H2B. Another Nap1 ·H2A-H2B·Kap114·Ran structure reveals the nuclear complex. Mutagenesis revealed shared critical interfaces in all three structures. Consistent with structural findings, DNA competition experiments demonstrated that Kap114 and Nap1 together chaperone H2A-H2B better than either protein alone. When RanGTP is present, Kap114's chaperoning activity diminishes. However, the presence of Nap1 within the Nap1 ·H2A-H2B·Kap114·Ran quaternary complex restores its ability to chaperone H2A-H2B. This complex effectively deposits H2A-H2B into nucleosomes. Together, these findings suggest that Kap114 and Nap12 provide a sheltered path from cytoplasm to nucleus, facilitating the transfer of H2A-H2B from Kap114 to Nap1 , ultimately directing its specific deposition into nucleosomes. | ||||||||||||||||||
History |
|
-
Structure visualization
Structure viewer | Molecule: ![]() ![]() |
---|
-
Downloads & links
-
Download
PDBx/mmCIF format | ![]() | 113.7 KB | Display | ![]() |
---|---|---|---|---|
PDB format | ![]() | 86.9 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
Others | ![]() |
-Validation report
Summary document | ![]() | 1.1 MB | Display | ![]() |
---|---|---|---|---|
Full document | ![]() | 1.1 MB | Display | |
Data in XML | ![]() | 33.1 KB | Display | |
Data in CIF | ![]() | 46.9 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 44095MC ![]() 9b31C ![]() 9b3fC ![]() 9b3iC M: map data used to model this data C: citing same article ( |
---|---|
Similar structure data | Similarity search - Function & homology ![]() |
-
Links
-
Assembly
Deposited unit | ![]()
|
---|---|
1 |
|
-
Components
#1: Protein | Mass: 36182.355 Da / Num. of mol.: 2 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() Gene: NAP1, GI527_G0003692 / Production host: ![]() ![]() Has protein modification | N | |
---|
-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
---|---|
EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
-
Sample preparation
Component | Name: Complex of Kap114 bound to Nap1 and histone H2A-H2B / Type: COMPLEX / Details: crosslinked sample. / Entity ID: all / Source: RECOMBINANT | |||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Molecular weight | Value: 0.072 MDa / Experimental value: NO | |||||||||||||||||||||||||
Source (natural) | Organism: ![]() ![]() | |||||||||||||||||||||||||
Source (recombinant) | Organism: ![]() ![]() | |||||||||||||||||||||||||
Buffer solution | pH: 7.4 | |||||||||||||||||||||||||
Buffer component |
| |||||||||||||||||||||||||
Specimen | Conc.: 1.2 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES / Details: Crosslinked sample. | |||||||||||||||||||||||||
Specimen support | Grid material: COPPER / Grid mesh size: 300 divisions/in. / Grid type: Quantifoil | |||||||||||||||||||||||||
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 95 % / Chamber temperature: 280 K |
-
Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
---|---|
Microscopy | Model: FEI TITAN KRIOS |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal magnification: 105000 X / Nominal defocus max: 2400 nm / Nominal defocus min: 900 nm |
Specimen holder | Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER |
Image recording | Average exposure time: 5.4 sec. / Electron dose: 59 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) / Num. of grids imaged: 1 / Num. of real images: 1080 |
EM imaging optics | Energyfilter slit width: 20 eV |
-
Processing
EM software |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Particle selection | Num. of particles selected: 4314112 Details: Blob picking on 100 micrographs and then further template picking. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
3D reconstruction | Resolution: 3.2 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 230210 / Symmetry type: POINT | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Atomic model building | Protocol: OTHER | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Atomic model building | Details: AlphaFold Multimer was used to generate initial model. Source name: AlphaFold / Type: in silico model | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Refine LS restraints |
|