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Updated: Oct 1, 2026

Preparation of Nucleosome Core Particles Complexed with DNA Repair Factors for Cryo-Electron Microscopy Structural Determination
Published on: August 17, 2022
Cryo-EM structures of CENP-A nucleosomes isolated from human cells
Eisho Tanida1,2, Suguru Hatazawa1, Takumi Oishi1,2
1Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan.
Abstract:
Centromeres ensure accurate chromosome segregation, and their identity is specified epigenetically by the histone H3 variant CENP-A. Although the structures of reconstituted CENP-A nucleosomes have provided important insights, how this epigenetic mark is structurally organized within native chromatin remains incompletely understood. Here, we combine cryogenic electron microscopy with chromatin immunoprecipitation (ChIP-CryoEM) to determine the structures of human CENP-A nucleosomes isolated directly from cells without crosslinking or stabilizing agents. We resolved two distinct cellular CENP-A nucleosome structures: a homotypic CENP-A nucleosome and a heterotypic CENP-A/H3 nucleosome, which have been proposed to represent centromeric and ectopic nucleosomes, respectively. Both cellular CENP-A nucleosomes assemble as histone octamers and wrap DNA in a left-handed superhelix, supporting an octameric model proposed for native CENP-A chromatin. In addition, the hallmark CENP-A-specific structural features previously characterized in vitro, including the shortened CENP-A N-terminal α-helix and the distinctive RG loop, are preserved in cellular CENP-A nucleosomes. These findings define the structural organization of CENP-A nucleosomes in cellular chromatin.
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