Histone chaperone Nap1 facilitates histone dynamics in the nucleosome

Abstract

We developed a single‐molecule FRET (smFRET) experimental system with which we can separately monitor histone H2A‐H2B dimer dynamics and DNA dynamics within a nucleosome particle. Utilizing the system, we monitored the nucleosome dynamics in the presence of histone chaperone Nap1 in order to investigate how the chaperone alters the dynamics of the nucleosome with and without histone acetylations at H3K56 and H4K16. We also compared the nucleosome dynamics in the presence of Nap1 to that in its absence at an elevated salt concentration. Our results indicate that DNA unwraps out of the nucleosome before histone dimer moves at an elevated salt concentration of 650 mM NaCl. On the contrary, we observe over 60 % of the nucleosomes show dimer motion prior to DNA unwrapping in the presence of Nap1. Upon monitoring the DNA unwrapping kinetics with histone acetylation at H3K56 or H4K16, we found that DNA unwrapping becomes facilitated mainly by destabilizing the fully wrapped nucleosomal state. Our results strongly suggest that Nap1 would have a direct impact on RNA polymerase II progression through the nucleosome, which we have also confirmed with our system, and that histone acetylations would amplify this effect in the presence of Nap1.Support or Funding InformationNIH [GM097286]This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.