まとめ
DNAの包装の重要な構成要素であるヒストンオクトーマーには,巻き状の構造があります. 個々のヒストンで構成されるこの構造は,DNAが核細胞内でどのように包まれているかを説明します.
科学分野:
- 構造生物学 構造生物学とは
- 分子遺伝学 分子遺伝学
- バイオケミストリー バイオケミストリー
背景:
- 核体は,真核生物におけるDNA包装の基本単位である.
- 核細胞内のヒストンの正確な配置を理解することは,遺伝子調節の解読に不可欠です.
- 以前の研究では,ヒストンオクタマーの構造の解像度が限られていた.
研究 の 目的:
- ヒストンオクターマーの高解像度構造を決定する.
- 核体内の個々のヒストンタンパク質の配置を解明する.
- ヒストンオクターマーの周りのDNAの巻き回りのモデルを提案する.
主な方法:
- 高解像度画像の再構築 (22 Å 解像度).
- ヒストンオクターマー (H3) 2 (H4) 2 (H2A) 2 (H2B) 2の分析
- 相互リンク研究を統合する.
主要な成果:
- ヒストンのオクトーマーには2重の対称性軸があります.
- その形状は,左利き螺旋のホイールに似ています.
- DNAは,約2回転の回転で,平らなスーパーヘリックスでこの spool の周りに巻き込まれています.
結論:
- 構造に基づいて個々のヒストンの詳細な配置が提案されています.
- (H3) 2 (H4) 2テトラメアは中央の円盤を形成する.
- 2つのH2A-H2Bダイマーが対極面に配置され,DNAと相互作用します.
関連する概念動画
02:33The Nucleosome
DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside the nucleus is astonishing. It is organized into several sequentially higher levels of compaction to fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
02:10The Nucleosome Core Particle
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
02:21Chromatin Packaging
Each human somatic cell contains 6 billion base-pairs of DNA. Each base-pair is 0.34 nm long, which means that each diploid cell contains a staggering 2 meters of DNA. How is such a long DNA strand packed inside a nucleus measuring only 10 - 20 microns in diameter?
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
02:33The Nucleosome
DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside the nucleus is astonishing. It is organized into several sequentially higher levels of compaction to fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
01:19The Nucleosome
Human DNA is almost two meters long. However, it is compressed inside a tiny nucleus measuring only a few microns in diameter. To make this degree of compaction possible, DNA is organized into several sequential levels so that it can fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
01:12The Nucleosome Core Particle
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...