UFM1 E3リガゼは,ERトランスロコンから60Sリボソームを認識して放出する
Linda Makhlouf1, Joshua J Peter2, Helge M Magnussen2
1Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
Nature
|February 21, 2024
まとめ
UFM1リボソームE3リガゼ (UREL) 複合体は,停止したリボソームを修正し,ER膜から放出を促進します. このUFMylationプロセスは,タンパク質ホメオスタシスに不可欠であり,リボソームをSEC61トランスロコンから分離することによってリサイクルします.
科学分野:
- 分子生物学
- 細胞生物学
- 構造生物学
背景:
- エンドプラズマ網膜 (ER) での停止したリボソームは,60Sリボソームサブユニット (RPL26) のユビキチンのようなタンパク質UFM1によって改変される.
- このUFMylationと呼ばれるプロセスは,UFL1,UFBP1,CDK5RAP3で構成されるUFM1リボソームE3リガゼ (UREL) 複合体によって媒介されます.
- URELの正確な触媒メカニズムとUFMylationの機能的結果は,大部分が未決定のままである.
研究 の 目的:
- URELの基板特異性の構造的基礎を明らかにする.
- ERにおけるリボソームリサイクルとタンパク質ホメオスタシスにおけるUFMylationの機能的影響を理解する.
- SEC61トランスロコンからのリボソームの解離におけるUFMylationの役割を調査する.
主な方法:
- 60Sリボソームに結合したUREL複合体の構造を決定するために,冷凍電子顕微鏡 (cryo-EM) が使用された.
- 60SサブユニットからSEC61を放出するためにUFMylationの必要性を評価するために生化学的測定法を使用した.
- URELの構造的特徴と機能的状態 ("ライター"と"リーダー"モジュール) の分析が行われました.
主要な成果:
- クリオ-EM構造は,URELが60Sサブユニット周りにC形のクランプを形成し,tRNA結合部位とペプチド出口トンネルを阻害することを明らかにします.
- UREL内のUFL1ループはペプチジルトランスファーゼセンターを再構成し,リボソームの放出とリサイクルにおける役割を示唆しています.
- 機能的研究では,UFMylationは,SEC61トランスロコンから60Sサブユニットを分離するために不可欠であり,ER膜での蓄積を防止します.
結論:
- URELのクランプのような構造とペプチジルトランスファーゼセンターとの相互作用は,リボソーム放出におけるその機能の鍵です.
- UFMylationは,ER膜から停滞したリボソームを解放し,効率的なタンパク質ホメオスタシスを確保する重要なステップです.
- URELは,UFMylationの"ライター"と"リーダー"の両方として機能し,リボソームリサイクルのためのユニークな規制メカニズムを強調します.
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