核群によるcGAS阻害の構造的メカニズム
Ganesh R Pathare1,2, Alexiane Decout3, Selene Glück3
1Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
Nature
|September 10, 2020
まとめ
クロマチンの結合は,モノメア状態に閉じ込め,ゲノムDNAによる偽活性化を防ぐことで,サイクルGMP- AMP合成酵素 (cGAS) を阻害する. この構造的な洞察は,cGASが自己と非自己のDNAを区別する方法を明らかにします.
科学分野:
- 免疫学
- 構造生物学
- 分子生物学
背景:
- 循環型GMP-AMP合成酵素 (cGAS) は,感染症,ストレス,癌に反応する先天的な免疫に不可欠なDNAセンサーです.
- サイトゾリックcGASは,2'- 3'- cGMP- AMPを二重鎖DNAの検出により生成し,炎症性サイトカインとI型インターフェロンを誘発する.
- 核のcGAS活動はクロマチンによって制限されるが,この抑制の構造的根拠は不明である.
研究 の 目的:
- ヒトのcGASのクロマチン媒介抑制の構造的基礎を明らかにする.
- cGASが自己 (ゲノム) と非自己DNAを区別するメカニズムを理解する.
主な方法:
- クリオ電子顕微鏡で,ヒトのcGASが核細胞に結合する構造を決定する.
- cGAS-ニュクレオソームの相互作用を調査するための生化学分析
- 機能的影響を評価するために変異cGASを用いた細胞ベースの測定法.
主要な成果:
- 構造は,cGAS,ヒストンH2A-H2B酸性パッチ,および核細胞DNAの間の広範な接触を明らかにします.
- cGASはトランスにおける第2のヌクレオソームと結合し,その活性化をステリカルに阻害するモノメア状態を採用する.
- cGASと酸性パッチのインターフェースの変異は,in vitroで核細胞阻害をなくし,細胞内のゲノムDNAによるcGAS活性化を可能にします.
結論:
- この研究は,クロマチンとのcGAS相互作用の構造的基礎を明らかにした.
- 核細胞結合はcGASを不活性なモノマーに鎖し,ゲノムDNAによる偽活性化を防ぐ.
- このメカニズムにより,cGASは自己のDNAと非自己のDNAを区別することができ,免疫監視に不可欠です.
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