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Updated: Dec 30, 2025

Probing The Structure And Dynamics Of Nucleosomes Using Atomic Force Microscopy Imaging
Published on: January 31, 2019
Free energy profile for unwrapping outer superhelical turn of CENP-A nucleosome
Hidetoshi Kono1, Shun Sakuraba1, Hisashi Ishida1
1Molecular Modelling and Simulation Group, Institute for Quantum Life Science (iQLS), National Institutes for Quantum and Radiological Science and Technology, Kizugawa, Kyoto 619-0215 Japan.
Abstract:
Eukaryotic genome is packaged in a nucleus in the form of chromatin. The fundamental structural unit of the chromatin is the protein-DNA complex, nucleosome, where DNA of about 150 bp is wrapped around a histone core almost twice. In cellular processes such as gene expression, DNA repair and duplication, the nucleosomal DNA has to be unwrapped. Histone proteins have their variants, indicating there are a variety of constitutions of nucleosomes. These different constitutions are observed in different cellular processes. To investigate differences among nucleosomes, we calculated free energy profiles for unwrapping the outer superhelical turn of CENP-A nucleosome and compared them with those of the canonical nucleosome. The free energy profiles for CENP-A nucleosome suggest that CENP-A nucleosome is the most stable when 16 to 22 bps are unwrapped in total whereas the canonical nucleosome is the most stable when it is fully wrapped. This indicates that the flexible conformation of CENP-A nucleosome is ready to provide binding sites for the structural integrity of the centromere.
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