Structural evidence for Nap1-dependent H2A-H2B deposition and nucleosome assembly

EMBO J. 2016 Jul 1;35(13):1465-82. doi: 10.15252/embj.201694105. Epub 2016 May 25.


Nap1 is a histone chaperone involved in the nuclear import of H2A-H2B and nucleosome assembly. Here, we report the crystal structure of Nap1 bound to H2A-H2B together with in vitro and in vivo functional studies that elucidate the principles underlying Nap1-mediated H2A-H2B chaperoning and nucleosome assembly. A Nap1 dimer provides an acidic binding surface and asymmetrically engages a single H2A-H2B heterodimer. Oligomerization of the Nap1-H2A-H2B complex results in burial of surfaces required for deposition of H2A-H2B into nucleosomes. Chromatin immunoprecipitation-exonuclease (ChIP-exo) analysis shows that Nap1 is required for H2A-H2B deposition across the genome. Mutants that interfere with Nap1 oligomerization exhibit severe nucleosome assembly defects showing that oligomerization is essential for the chaperone function. These findings establish the molecular basis for Nap1-mediated H2A-H2B deposition and nucleosome assembly.

Keywords: H2A–H2B; Nap1; chromatin; histone chaperone; nucleosome assembly.

MeSH terms

  • Chromatin Immunoprecipitation
  • Crystallography, X-Ray
  • DNA Mutational Analysis
  • Histones / chemistry*
  • Histones / metabolism*
  • Models, Molecular
  • Nucleosome Assembly Protein 1 / chemistry*
  • Nucleosome Assembly Protein 1 / genetics
  • Nucleosome Assembly Protein 1 / metabolism*
  • Nucleosomes / metabolism*
  • Protein Binding
  • Protein Conformation
  • Protein Multimerization
  • Saccharomyces cerevisiae / chemistry
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*


  • Histones
  • NAP1 protein, S cerevisiae
  • Nucleosome Assembly Protein 1
  • Nucleosomes
  • Saccharomyces cerevisiae Proteins