RADAR超分子抗菌体防御複合体の冷凍-EM構造
Brianna Duncan-Lowey1, Nitzan Tal2, Alex G Johnson1
1Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
Cell
|February 10, 2023
まとめ
RADARの細菌防御システムはRdrAとRdrBのタンパク質を使ってATPをITPに変換し,ファグの複製を制限する. このニュクレオチドの変異は RADARの鍵です
科学分野:
- 細菌の免疫と防御メカニズム
- 構造生物学と冷凍電子顕微鏡
- 核酸代謝の分子メカニズム
背景:
- RADAR (DNA関連活性認識) は細菌の防御システムです
- 以前は,メッセンジャーRNAを改変することによって,細菌菌に対して防御することが理解されていました.
- 詳細な分子構造とメカニズムは ほとんど不明でした
研究 の 目的:
- RADAR防衛複合体の冷凍電子顕微鏡 (cryo-EM) 構造を決定する.
- RADARが抗菌体免疫を与える分子メカニズムを解明する.
- 防衛に関わる特定の核酸変異を特定する.
主な方法:
- RADAR複合体の高解像度構造を解明するための冷凍電子顕微鏡 (冷凍EM).
- 酵素活性を in vitro で試験する生化学的測定法
- 細菌菌感染中の核酸の蓄積を観察するインビボ実験.
主要な成果:
- Cryo-EM構造は,RdrAをヘプタメリクAAA+ ATPaseと,RdrBをデアミナーゼ活性部位を持つドデカメリク複合体として明らかにした.
- RdrAとRdrBは,RdrAがRdrBの活性部位の上に配置されている大きなアセンブリ (最大10MDa) を形成します.
- RdrBはインビトロでATPをイノシン三リン酸 (ITP) に変換し,ファグ感染中にITPの蓄積につながり,ファグの複製を阻害する.
結論:
- RADAR免疫は,RNA編集ではなく,ATPモノヌクレオチド除去によって決定される.
- この研究は,ニュクレオチド改変装置の超分子組成を通して,抗菌素防御の新しいメカニズムを明らかにしています.
- この研究は 細菌防御における RADARシステムの機能を 再定義しています
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