Chaperone Nap1 shields histone surfaces used in a nucleosome and can put H2A-H2B in an unconventional tetrameric form. Journal Article uri icon



  • The histone H2A-H2B heterodimer is an integral component of the nucleosome. The cellular localization and deposition of H2A-H2B into chromatin is regulated by numerous factors, including histone chaperones such as nucleosome assembly protein 1 (Nap1). We use hydrogen-deuterium exchange coupled to mass spectrometry to characterize H2A-H2B and Nap1. Unexpectedly, we find that at low ionic strength, the α helices in H2A-H2B are frequently sampling partially disordered conformations and that binding to Nap1 reduces this conformational sampling. We identify the interaction surface between H2A-H2B and Nap1 and confirm its relevance both in vitro and in vivo. We show that two copies of H2A-H2B bound to a Nap1 homodimer form a tetramer with contacts between H2B chains similar to those in the four-helix bundle structural motif. The organization of the complex reveals that Nap1 competes with histone-DNA and interhistone interactions observed in the nucleosome, thereby regulating the availability of histones for chromatin assembly.

publication date

  • September 12, 2013

has subject area

Full Author List

  • D'Arcy S; Martin KW; Panchenko T; Chen X; Bergeron S; Stargell LA; Black BE; Luger K

Other Profiles

Additional Document Info

start page

  • 662

end page

  • 677


  • 51


  • 5