2025-05-14 東京科学大学
図1. 染色体の模式図とCENP-A-H4オクタソームの構造
染色体のセントロメア領域に存在すると考えられてきたCENP-AヌクレオソームとCENP-A-H4オクタソームの比較。本研究で発見したCENP-A-H4オクタソームは、従来のCENP-Aヌクレオソームの2倍のCENP-Aを持っている。
<関連情報>
- https://www.isct.ac.jp/ja/news/u64tqnk3izfm
- https://www.isct.ac.jp/plugins/cms/component_download_file.php?type=2&pageId=&contentsId=1&contentsDataId=1543&prevId=&key=26ab927c6b9506e8a0b2fd7100d83b46.pdf
- https://onlinelibrary.wiley.com/doi/10.1111/gtc.70016
セントロメア特異的ヒストン変異体CENP-Aを含むユニークなサブヌクレオソームの低温電子顕微鏡解析 Cryo-EM Analysis of a Unique Subnucleosome Containing Centromere-Specific Histone Variant CENP-A
Osamu Kawasaki, Yoshimasa Takizawa, Iori Kiyokawa, Hitoshi Kurumizaka, Kayo Nozawa
Genes to Cells Published: 24 March 2025
DOI:https://doi.org/10.1111/gtc.70016
ABSTRACT
In eukaryotes, genomic DNA is stored in the nucleus as nucleosomes, in which a DNA segment is wrapped around a protein octamer consisting of two each of the four histones, H2A, H2B, H3, and H4. The core histones can be replaced by histone variants or altered with covalent modifications, contributing to the regulation of chromosome structure and nuclear activities. The formation of an octameric histone core in nucleosomes is widely accepted. Recently, the H3–H4 octasome, a novel nucleosome-like structure with a histone octamer consisting solely of H3 and H4, has been reported. CENP-A is the centromere-specific histone H3 variant and determines the position of kinetochore assembly during mitosis. CENP-A is a distant H3 variant sharing approximately 50% amino acid sequence with H3. In this study, we found that CENP-A and H4 also formed an octamer without H2A and H2B in vitro. We determined the structure of the CENP-A–H4 octasome at 3.66 Å resolution. In the CENP-A–H4 octasome, an approximately 120-base pair DNA segment was wrapped around the CENP-A–H4 octameric core and displayed the four CENP-A RG-loops, which are the direct binding sites for another centromeric protein, CENP-N.
