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In Vitro Characterization of Histone Chaperones using Analytical, Pull-Down and Chaperoning Assays
Published on: December 29, 2021
The nuclear transport machinery recognizes nucleoplasmin-histone complexes
Igor Arregi1, Jorge Falces, Sonia Bañuelos
1Unidad de Biofísica (CSIC/UPV-EHU), Departamento de Bioquí́mica y Biologí́a Molecular, Universidad del Paí́s Vasco, POB 644, 48080 Bilbao, Spain.
Biochemistry
|July 26, 2011
Summary
This study reveals that nucleoplasmin (NP) and histones can form complexes with importins, suggesting a co-transport mechanism for nuclear import. This pathway enhances the efficiency of histone and NP delivery to the nucleus.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Transport
Background:
- Nuclear transport of proteins like nucleoplasmin (NP) and histones is crucial for chromatin regulation.
- Importins mediate this transport, with NP using a classical nuclear localization signal (NLS) and histones utilizing NLS-like motifs.
Purpose of the Study:
- To investigate the potential co-transport of histones and their chaperone, nucleoplasmin (NP), to the nucleus.
- To analyze the assembly and binding characteristics of NP/histone complexes with importins.
Main Methods:
- Fluorescence anisotropy
- Sucrose gradient centrifugation
- Isothermal titration calorimetry
Main Results:
- Importin α ΔIBB and histones (linker and core) can bind simultaneously to NP, forming high-affinity ternary complexes.
- The binding stoichiometry of importin α to NP/histone complexes varies with histone type and quantity.
- NP/histone complexes can incorporate importin α/β, forming quaternary complexes.
Conclusions:
- A putative co-import pathway for histones and NP to the nucleus exists.
- This pathway involves the formation of quaternary NP/histone/importin complexes.
- This co-transport mechanism likely enhances the efficiency of nuclear import for histones and NP.
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