転位リボソームに関するtmRNA-SmpBとEF-Gの複合体
David J F Ramrath1, Hiroshi Yamamoto, Kristian Rother
1Institut für Medizinische Physik und Biophysik, Charite - Universitätsmedizin Berlin, Ziegelstrasse 5-9, 10117 Berlin, Germany.
Nature
|May 25, 2012
まとめ
バクテリアのリボソームは,トランスファーメッセンジャーRNA (tmRNA) とSmpBタンパク質を使用して,停止した翻訳を救出します. 新しい30Sヘッドの回転メカニズムは,tmRNAの転位とmRNAの負荷を非正規の経路に容易にします.
科学分野:
- 分子生物学は分子生物学である.
- 構造生物学 構造生物学とは
- 微生物学 微生物学とは
背景:
- バクテリアのリボソームは,機能不全したメッセンジャーRNA (mRNA) で停滞することがあります.
- 転送メッセンジャーRNA (tmRNA) 媒介のトランストランスレーションは,これらの停滞したリボソームを救う.
- SmpBタンパク質はtmRNAと複合体を形成し,リボソームとの相互作用を促進します.
研究 の 目的:
- トランストランスレーション中のtmRNA転位とmRNA負荷の構造的メカニズムを解明する.
- リボソームが大きくて構造的なtmRNA分子にどのように適応するかを理解する.
- この非法典的な翻訳プロセスにおける延長因子EF-Gの役割を調査する.
主な方法:
- 低温電子顕微鏡 (cryo-EM) を用いて,フジド酸で停止したリボソーム70S-tmRNA-SmpB-EF-G複合体を再構築した.
- 高解像度 (8.3 Å) 構造分析によるトランスロケーション後の中間物質 (TI(POST)).
主要な成果:
- 30Sリボソームヘッドの独特で大きな回転運動が確認されました.
- この回転カップルは,tmRNA-SmpBトランスロケーションを,tmRNAのmRNAのようなドメイン (MLD) のロードに結び付けます.
- TLD-SmpBモジュールはap/Pハイブリッドサイトで,tRNA (fMet) はpe/Eハイブリッドサイトで観察されました.
結論:
- 30Sヘッド・スウィーバーは,tmRNAの転位とMLDの負荷を可能にする重要なメカニズムです.
- このプロセスは,リボソームのダイナミックで多用途な性質を強調しています.
- リボソームの構成動態は,トランストランスレーションのような非法典的経路に特化するために再利用できます.
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