枝分かれ直後のスプライソームの冷凍-EM構造
Wojciech P Galej1, Max E Wilkinson1, Sebastian M Fica1
1MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
Nature
|July 27, 2016
まとめ
スプライソーム
科学分野:
- 分子生物学
- 構造生物学
- 生物化学
背景:
- 先駆者メッセンジャーRNA (pre-mRNA) スプライシングは基本的な生物学的プロセスです.
- スプライシングは2つの触媒のステップで,ラリアット-イントロンの中間物質を形成します.
- スプライソームという 巨大な分子機構が この過程を指揮しています
研究 の 目的:
- ラリアト形成直後のスプライソームの構造的動態を解明する.
- スプライセソームの分子構造を,スプライシングの重要な中間段階で視覚化する.
主な方法:
- 構造を決定するために,冷凍電子顕微鏡 (cryo-EM) が使用されました.
- スプライソーム複合体の高解像度 (3. 8 Å) の構造データは得られた.
主要な成果:
- 構造は5'-spliceサイトが割れたが,触媒Mg2+サイトに近いことを示している.
- イントロンの5'-リン酸は,枝状アデノシンと結合している.
- U2/U6 snRNA,U5 snRNA,およびスプライシング因子 (Isy1,Yju2,Cwc25) が関与する特定の相互作用は,ラリアト中間物質を安定させる.
- 5'-エクソンは,その後の結合のために位置づけられています.
結論:
- 凍結-EM構造は,スプライソームの形状形成後の前例のない洞察を提供します.
- この構造は,ラリアト中間物質の安定化のための分子基盤を明確にし,第二のスプライシングステップのためのコンポーネントを配置します.
- この発見は,エクソン結合前にイントロン再構成のメカニズムを示唆している.
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