Shearing of the CENP-A dimerization interface mediates plasticity in the octameric centromeric nucleosome

Sci Rep. 2015 Nov 25:5:17038. doi: 10.1038/srep17038.

Abstract

The centromeric nucleosome is a key epigenetic determinant of centromere identity and function. Consequently, deciphering how CENP-A containing nucleosomes contribute structurally to centromere function is a fundamental question in chromosome biology. Here, we performed microsecond timescale all-atom molecular dynamics (MD) simulations of CENP-A and H3 nucleosomes, and report that the octameric CENP-A core particles and nucleosomes display different dynamics from their canonical H3-containing counterparts. The most significant motion observed is within key interactions at the heart of the CENP-A octameric core, wherein shearing of contacts within the CENP-A:CENP-A' dimerization interface results in a weaker four helix bundle, and an extrusion of 10-30 bp of DNA near the pseudo-dyad. Coupled to other local and global fluctuations, the CENP-A nucleosome occupies a more rugged free energy landscape than the canonical H3 nucleosome. Taken together, our data suggest that CENP-A encodes enhanced distortability to the octameric nucleosome, which may allow for enhanced flexing of the histone core in vivo.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Autoantigens / chemistry
  • Autoantigens / metabolism*
  • Centromere / metabolism
  • Centromere Protein A
  • Chromosomal Proteins, Non-Histone / chemistry
  • Chromosomal Proteins, Non-Histone / metabolism*
  • DNA / chemistry
  • DNA / metabolism
  • Dimerization
  • Histones / metabolism
  • Humans
  • Molecular Dynamics Simulation
  • Nucleosomes / chemistry
  • Nucleosomes / metabolism*
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Static Electricity

Substances

  • Autoantigens
  • CENPA protein, human
  • Centromere Protein A
  • Chromosomal Proteins, Non-Histone
  • Histones
  • Nucleosomes
  • DNA