Biophysics and Physicobiology
Online ISSN : 2189-4779
ISSN-L : 2189-4779
Regular Article
Free energy profile for unwrapping outer superhelical turn of CENP-A nucleosome
Hidetoshi KonoShun SakurabaHisashi Ishida
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Supplementary material

2019 Volume 16 Pages 337-343

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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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© 2019 THE BIOPHYSICAL SOCIETY OF JAPAN
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