異体化 ヒストン H4 の 半合成 は,染色体 の 頑丈 さ と 分子 の 老化 に 対する 脆弱 さ を 明らか に し ます
Tianze Zhang1, Luis F Guerra1, Yana Berlina2
1Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, U.K.
Journal of the American Chemical Society
|February 3, 2025
まとめ
タンパク質の老化により,アスパルチン酸 (Asp) がアイソアスパルチン酸 (isoAsp) を形成する. 24位 (H4isoD24) にあるヒストンH4を研究した. H4isoD24はヒストンのメチル化に影響するが,クロマチンの圧縮や再構成には影響しない.
科学分野:
- 生物化学
- 分子生物学
- エピジェネティクス
背景:
- タンパク質は,自発的,非酵素的な翻訳後の改変 (PTM) を経由して老化します.
- アスパルチン酸 (Asp) またはアスパルチン残基からアイソアスパルチン酸 (isoAsp) の形成は,長寿タンパク質における一般的なPTMである.
- 長い半減期を持つヒストンは,ISOAspの形成に敏感で,クロマチンの構造と機能に影響します.
研究 の 目的:
- ヒストンH4におけるイソアスパルティック酸 (isoAsp) 形成の分子的影響を調査する.
- タンパク質半合成を用いて,位置24 (H4isoD24) で isoAspを持つ全長ヒストンH4変異体を生成し,特徴づけること.
- H4isoD24がクロマチンの凝縮,核細胞再構成,ヒストンのメチル化に与える影響を評価する.
主な方法:
- H4isoD24の変種を作るためにタンパク質半合成が用いられました.
- H4isoD24を含むクロマチンのテンプレートを組み立てました.
- In vitroアッセイは,Mg2+媒介のクロマチンの自己結合,Chd1による核細胞再構成,およびSet8とSuv4-20h1によるH4K20メチレーションを評価するために使用された.
主要な成果:
- H4isoD24は,Mg2+媒介のクロマチンの自己結合を有意に妨げなかった.
- リモデラー Chd1による核細胞の再定位は,H4isoD24の存在によってほとんど影響を受けなかった.
- H4isoD24は,H4K20でSet8とSuv4-20h1によって触媒化されたメチル化を有意に抑制した.
結論:
- ヒストンH4におけるイソアスパルティック酸の改変は,クロマチンの機能的構造の複雑な再編成につながります.
- H4isoD24に対する圧縮と再構成のようなマクロクロマチンのプロセスは頑丈である.
- 局所的なメカニズム,特にH4K20メチレーションは,ヒストンのイソアスパル酸変異の存在に対して脆弱である.
関連する概念動画
Histone Modification
13.0K
The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone...
13.0K
Spreading of Chromatin Modifications
8.2K
The histone proteins in the nucleosomes are post-translationally modified (PTM) to increase or decrease access to DNA. The commonly observed PTMs are methylation, acetylation, phosphorylation, and ubiquitination of lysine amino acids in the histone H3 tail region. These histone modifications have specific meaning for the cell. Hence, they are called "histone code". The protein complex involved in histone modification is termed as "reader-writer" complex.
Writers
The writer...
Writers
The writer...
8.2K
Heterochromatin
10.0K
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions that take up more dye are called heterochromatin. Heterochromatin is further classified into two forms – constitutive heterochromatin and facultative heterochromatin.
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at...
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at...
10.0K
Inheritance of Chromatin Structures
6.2K
Epigenetics is the study of inherited changes in a cell's phenotype without changing the DNA sequences. It provides a form of memory for the differential gene expression pattern to maintain cell lineage, position-effect variegation, dosage compensation, and maintenance of chromatin structures such as telomeres and centromeres. For example, the structure and location of the centromere on chromosomes are epigenetically inherited. Its functionality is not dictated or ensured by the underlying...
6.2K
Chromatin Modification in iPS Cells
1.6K
Chromatin modification alters gene expression; therefore, scientists can add histone-modifying enzymes, histone variants, and chromatin remodeling complexes to somatic cells to aid reprogramming into pluripotent stem (iPS) cells.
Compact chromatin makes reprogramming difficult. Enzymes, such as histone demethylases and acetyltransferases, are often added during reprogramming to loosen the chromatin, making the DNA more accessible to transcription factors. Molecules that inhibit histone...
Compact chromatin makes reprogramming difficult. Enzymes, such as histone demethylases and acetyltransferases, are often added during reprogramming to loosen the chromatin, making the DNA more accessible to transcription factors. Molecules that inhibit histone...
1.6K
Histone Variants at the Centromere
4.3K
Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as “mutant” forms that replace their canonical histone counterparts in the nucleosomes. Specific post-translational modifications on the histone variants enable further chromatin complexity and regulate tissue-specific gene expression. The most common histone variants are from histone H2A, H2B, and linker histone H1 families. However, several variants of histone H3...
4.3K


