タンパク質-DNAの相互作用のマッピング in vivo フォーマルデヒド:ヒストンH4が高度に転写された遺伝子に保持されている証拠
M J Solomon1, P L Larsen, A Varshavsky
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Cell
|June 17, 1988
まとめ
この研究では,ヒストンH4が熱ショックタンパク質70 (hsp70) の遺伝子に結合し,活体転写中にいても,in vivoで結合し続けることを明らかにしました. フォーマルアルデヒドのクロスリンク技術で,インビヴォのタンパク質-DNA相互作用とクロマチンの構造をマッピングします.
科学分野:
- 分子生物学は分子生物学である.
- 遺伝学 遺伝学とは
- クロマチンの生物学
背景:
- 生体内クロマチンの構造を理解することは,遺伝子調節にとって極めて重要です.
- 以前のin vitro研究では,活性転写中にヒストンの除去が示唆されていたが,in vivoでは証拠が不足していた.
研究 の 目的:
- ドロソフィラ・メラロナガスターの熱ショックタンパク質70 (hsp70) 遺伝子のインビボ染色体構造を調査する.
- ヒストンが活に転写された遺伝子と関連しているかどうかを in vivo で判定する.
主な方法:
- 形甲酸媒介のタンパク質-DNAのクロスリンクは,無傷の細胞内で行われます.
- in vivoでクロスリンクされたクロマチンの断片の免疫圧縮.
- hsp70遺伝子の染色体構造とヒストン結合の分析.
主要な成果:
- 熱ショック誘導はhsp70遺伝子の染色体構造を変化させ,in vivoのタンパク質-DNA接触を減少させます.
- ヒストンH4は,転写活動に関係なく,hsp70DNAにインビヴォで結合し続けます.
- フォーマルアルデヒドベースのマッピング技術は,タンパク質とDNAの相互作用を in vivo で探査するのに有効です.
結論:
- ヒストンは,活体的に転写された遺伝子に必ずしも欠けているわけではありません.
- フォーマルデヒドのクロスリンクは,生体内クロマチンのダイナミクスとタンパク質-DNAの相互作用を研究するための貴重なツールを提供します.
- この方法は,タンパク質-DNAの相互作用をマッピングし,全ゲノムにわたる染色体タンパク質の位置を決定することができます.
関連する概念動画
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...
02:32Histone Modification
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 deacetylase,...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
02:25Spreading of Chromatin Modifications
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 is an enzyme that can...
Writers
The writer is an enzyme that can...
01:01Euchromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions take up more dye, appearing darker, while the less-compact areas take up less dye and appear lighter. Based on the compaction level, chromatins are classified into two primary forms – euchromatin and heterochromatin.
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
02:38Heterochromatin
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 9th...
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 9th...
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...