ct7b00936_si_001.pdf (1.66 MB)
Holding the Nucleosome Together: A Quantitative Description of the DNA–Histone Interface in Solution
journal contribution
posted on 2017-12-20, 00:00 authored by Ahmad Elbahnsi, Romain Retureau, Marc Baaden, Brigitte Hartmann, Christophe OgueyThe nucleosome is the fundamental
unit of eukaryotic genome packaging
in the chromatin. In this complex, the DNA wraps around eight histone
proteins to form a superhelical double helix. The resulting bending,
stronger than anything observed in free DNA, raises the question of
how such a distortion is stabilized by the proteic and solvent environments.
In this work, the DNA–histone interface in solution was exhaustively
analyzed from nucleosome structures generated by molecular dynamics.
An original Voronoi tessellation technique, measuring the topology
of interacting elements without any empirical or subjective adjustment,
was used to characterize the interface in terms of contact area and
occurrence. Our results revealed an interface more robust than previously
known, combining extensive, long-lived nonelectrostatic and electrostatic
interactions between DNA and both structured and unstructured histone
regions. Cation accumulation makes the proximity of juxtaposed DNA
gyres in the superhelix possible by shielding the strong electrostatic
repulsion of the charged phosphate groups. Overall, this study provides
new insights on the nucleosome cohesion, explaining how DNA distortions
can be maintained in a nucleoprotein complex.