CENP-A and H3 Nucleosomes Display a Similar Stability to Force-Mediated Disassembly
Sung Hyun Kim (TU Delft - BN/Cees Dekker Lab, Kavli institute of nanoscience Delft)
Rifka Vlijm (Kavli institute of nanoscience Delft, TU Delft - BN/Cees Dekker Lab)
Jaco van der Torre (Kavli institute of nanoscience Delft, TU Delft - BN/Technici en Analisten)
Y. Dalal (National Cancer Institute)
Cees Dekker (TU Delft - BN/Cees Dekker Lab, Kavli institute of nanoscience Delft)
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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.
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