Cryo-electron microscopy structure of the H3-H4 octasome: A nucleosome-like particle without histones H2A and H2B.
Kayo NozawaYoshimasa TakizawaLeonidas PierrakeasChizuru Sogawa-FujiwaraKazumi SaikusaSatoko AkashiEd LukHitoshi KurumizakaPublished in: Proceedings of the National Academy of Sciences of the United States of America (2022)
The canonical nucleosome, which represents the major packaging unit of eukaryotic chromatin, has an octameric core composed of two histone H2A-H2B and H3-H4 dimers with ∼147 base pairs (bp) of DNA wrapped around it. Non-nucleosomal particles with alternative histone stoichiometries and DNA wrapping configurations have been found, and they could profoundly influence genome architecture and function. Using cryo-electron microscopy, we solved the structure of the H3-H4 octasome, a nucleosome-like particle with a di-tetrameric core consisting exclusively of the H3 and H4 histones. The core is wrapped by ∼120 bp of DNA in 1.5 negative superhelical turns, forming two stacked disks that are connected by a H4-H4' four-helix bundle. Three conformations corresponding to alternative interdisk angles were observed, indicating the flexibility of the H3-H4 octasome structure. In vivo crosslinking experiments detected histone-histone interactions consistent with the H3-H4 octasome model, suggesting that H3-H4 octasomes or related structural features exist in cells.
Keyphrases
- electron microscopy
- circulating tumor
- cell free
- dna methylation
- single molecule
- genome wide
- induced apoptosis
- gene expression
- nucleic acid
- transcription factor
- dna damage
- cell cycle arrest
- endoplasmic reticulum stress
- signaling pathway
- oxidative stress
- cell death
- high resolution
- escherichia coli
- staphylococcus aureus
- pi k akt
- dna binding