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 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.
Biophysics Laboratories, Institute of Biomedical and Biomolecular Science, School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom.
Emily R
ER
Newman
G Geoff
GG
Kneale
Raimond B G
RB
Ravelli
Manikandan
M
Karuppasamy
Fatemeh
F
Karimi Nejadasl
Ian A
IA
Taylor
John E
JE
McGeehan
D000818:Animals; D002850:Chromatography, Gel; D020285:Cryoelectron Microscopy; D004591:Electrophoresis, Polyacrylamide Gel; D006657:Histones / Q000737:chemistry*; D056490:Nucleosome Assembly Protein 1 / Q000737:chemistry*; D053838:Scattering, Small Angle; D014461:Ultracentrifugation; D014961:X-Ray Diffraction; D014982:Xenopus laevis
D006657:Histones; D056490:Nucleosome Assembly Protein 1