Large multimeric assemblies of nucleosome assembly protein and histones revealed by small-angle X-ray scattering and electron microscopy

J Biol Chem. 2012 Aug 3;287(32):26657-65. doi: 10.1074/jbc.M112.340422. Epub 2012 Jun 15.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromatography, Gel
  • Cryoelectron Microscopy
  • Electrophoresis, Polyacrylamide Gel
  • Histones / chemistry*
  • Nucleosome Assembly Protein 1 / chemistry*
  • Scattering, Small Angle
  • Ultracentrifugation
  • X-Ray Diffraction
  • Xenopus laevis

Substances

  • Histones
  • Nucleosome Assembly Protein 1