CENP-A and H3 Nucleosomes Display a Similar Stability to Force-Mediated Disassembly

PLoS One. 2016 Nov 7;11(11):e0165078. doi: 10.1371/journal.pone.0165078. eCollection 2016.

Abstract

Centromere-specific nucleosomes are a central feature of the kinetochore complex during mitosis, in which microtubules exert pulling and pushing forces upon the centromere. CENP-A nucleosomes have been assumed to be structurally unique, thereby providing resilience under tension relative to their H3 canonical counterparts. Here, we directly test this hypothesis by subjecting CENP-A and H3 octameric nucleosomes, assembled on random or on centromeric DNA sequences, to varying amounts of applied force by using single-molecule magnetic tweezers. We monitor individual disassembly events of CENP-A and H3 nucleosomes. Regardless of the DNA sequence, the force-mediated disassembly experiments for CENP-A and H3 nucleosomes demonstrate similar rupture forces, life time residency and disassembly steps. From these experiments, we conclude that CENP-A does not, by itself, contribute unique structural features to the nucleosome that lead to a significant resistance against force-mediated disruption. The data present insights into the mechanistic basis for how CENP-A nucleosomes might contribute to the structural foundation of the centromere in vivo.

MeSH terms

  • Animals
  • Autoantigens / metabolism*
  • Biomechanical Phenomena
  • Centromere Protein A
  • Chromosomal Proteins, Non-Histone / metabolism*
  • DNA / metabolism
  • Histones / metabolism*
  • Humans
  • Kinetics
  • Mechanical Phenomena*
  • Nucleosomes / metabolism*
  • Xenopus laevis

Substances

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