CENP-A and H3 Nucleosomes Display a Similar Stability to Force-Mediated Disassembly.
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.
Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands.
Sung Hyun
SH
Kim
Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands.
Rifka
R
Vlijm
Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands.
Jaco
J
van der Torre
Chromatin Structure and Epigenetic Mechanisms Unit, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland, United States of America.
Yamini
Y
Dalal
Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands.
Cees
C
Dekker
D000818:Animals; D001324:Autoantigens / Q000378:metabolism*; D001696:Biomechanical Phenomena; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D055595:Mechanical Phenomena; D009707:Nucleosomes / Q000378:metabolism*; D014982:Xenopus laevis
D001324:Autoantigens; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D009707:Nucleosomes; D004247:DNA