ヒストン核粒子の長距離PELDOR測定について
Richard Ward1, Andrew Bowman, Hassane El-Mkami
1School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
Journal of the American Chemical Society
|January 14, 2009
まとめ
研究者らは,サイト・ディレクテッド・スピン・ラベリングとパルス電子パラマグネット共振 (EPR) を用いて,ヒストンオクタマー内の距離を測定した. この技術により,長距離距離測定が可能になり,クロマチンの構造に関する洞察が明らかになりました.
科学分野:
- 構造生物学 構造生物学とは
- バイオフィジックス 生物物理学
- 分子生物学は分子生物学である.
背景:
- 核素核粒子はクロマチンの基本単位である.
- 染色体構造のダイナミクスと機能を理解するには,その構成要素を調査する必要があります.
- H4,H3,H2A,H2Bから成るヒストンオクトーマーが核細胞の核を形成する.
研究 の 目的:
- 先進的な生体物理学技術を用いてヒストンオクタマーの構造とダイナミクスを探求する.
- ヒストン核粒子内の長距離距離を測定する.
- 結晶構造と比較して,スピンラベル付ヒストンオクタマーの構造的整合性を評価する.
主な方法:
- サイトダイレクトされたスピンラベル付けは,H3ヒストンに窒素酸化物スピンラベルを貼るためのものです.
- ラベル付けされたH3ヒストンの組立を機能的なヒストンオクタマーにします.
- パルス電子パラマグネティック共振 (EPR),特にPELDOR/DEER実験は,距離を測定するためのものです.
主要な成果:
- スピンラベルのヒストンオクタマーのPELDOR/DEER実験を成功裏に実施しました.
- 長期間にわたって明確に定義された二極振動が得られた.
- 60~70 Å の間の距離分布を導出し,生物系におけるこれまでで最も長く定義された測定値のいくつかを表しています.
- 確立された結晶構造からのわずかな偏差が観察されました.
結論:
- PELDOR/DEERと組み合わせたサイトダイレクトス・スピン・ラベリングは,ヒストンコア粒子のような生物学的システムにおける長距離測定に有効です.
- この結果は,ヒストン核粒子の構造的次元に関する貴重な洞察を提供します.
- この技術は,パルス式EPRの距離測定の限界に近づいている.
関連する概念動画
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...
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...
02:33The 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...
01:12The 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...
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...
01:32Chromatin Packaging
Each human somatic cell contains 6 billion base pairs of DNA. Each base pair is 0.34 nm long, meaning each diploid cell contains a staggering 2 meters of DNA. This long DNA strand is packed inside a nucleus measuring only 10-20 microns in diameter with the help of specialized DNA-binding proteins called histones. Together they form a compact DNA-protein complex called chromatin. The chromatin is further compacted into higher-order structures. The highest level of compaction is achieved during...