posted on 2021-06-29, 16:08authored byMohamad Zandian, Nicole Gonzalez Salguero, Matthew D. Shannon, Rudra N. Purusottam, Theint Theint, Michael G. Poirier, Christopher P. Jaroniec
Chromatin is a supramolecular DNA–protein
complex that compacts
eukaryotic genomes and regulates their accessibility and functions.
Dynamically disordered histone H3 N-terminal tails are among key chromatin
regulatory components. Here, we used high-resolution-magic-angle-spinning
NMR measurements of backbone amide 15N spin relaxation
rates to investigate, with residue-specific detail, the dynamics and
interactions of H3 tails in recombinant 13C,15N-enriched nucleosome arrays containing 15, 30, or 60 bp linker DNA
between the nucleosome repeats. These measurements were compared to
analogous data available for mononucleosomes devoid of linker DNA
or containing two 20 bp DNA overhangs. The H3 tail dynamics in nucleosome
arrays were found to be considerably attenuated compared with nucleosomes
with or without linker DNA due to transient electrostatic interactions
with the linker DNA segments and the structured chromatin environment.
Remarkably, however, the H3 tail dynamics were not modulated by the
specific linker DNA length within the 15–60 bp range investigated
here.