Large Multimeric Assemblies of Nucleosome Assembly Protein and Histones Revealed by Small-angle X-ray Scattering and Electron Microscopy

The nucleosome assembly protein (NAP) family represents a key group of histone chaperones that are essential for cell viability. Several x-ray structures of NAP1 dimers are available; however, there are currently no structures of this ubiquitous chaperone in complex with histones. We have characteri...

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Bibliographic Details
Published in:The Journal of biological chemistry 2012-08, Vol.287 (32), p.26657-26665
Main Authors: Newman, Emily R., Kneale, G. Geoff, Ravelli, Raimond B.G., Karuppasamy, Manikandan, Karimi Nejadasl, Fatemeh, Taylor, Ian A., McGeehan, John E.
Format: Article
Language:English
Subjects:
Analytical Ultracentrifugation
Animals
Biophysics
Chromatography, Gel
Cryoelectron Microscopy
Electron Microscopy (EM)
Electrophoresis, Polyacrylamide Gel
Histone Chaperone
Histones - chemistry
Molecular Biophysics
Nucleosome
Nucleosome Assembly Protein 1 - chemistry
Scattering, Small Angle
Ultracentrifugation
X-Ray Diffraction
X-ray Scattering
Xenopus laevis
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Summary:The nucleosome assembly protein (NAP) family represents a key group of histone chaperones that are essential for cell viability. Several x-ray structures of NAP1 dimers are available; however, there are currently no structures of this ubiquitous chaperone in complex with histones. We have characterized NAP1 from Xenopus laevis and reveal that it forms discrete multimers with histones H2A/H2B and H3/H4 at a stoichiometry of one NAP dimer to one histone fold dimer. These complexes have been characterized by size exclusion chromatography, analytical ultracentrifugation, multiangle laser light scattering, and small-angle x-ray scattering to reveal their oligomeric assembly states in solution. By employing single-particle cryo-electron microscopy, we visualized these complexes for the first time and show that they form heterogeneous ring-like structures, potentially acting as large scaffolds for histone assembly and exchange. Background: The nucleosome assembly protein (NAP) family facilitates the dynamic assembly of nucleosomes. Results: We reveal the large molecular assemblies of NAP-histone complexes. Conclusion: NAP-histone complexes assemble to form a heterogeneous population of ring-like scaffolds. Significance: Knowledge of the oligomeric states of NAP-histone complexes is crucial for understanding their diverse functions.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M112.340422