ユカリオットにおけるストップコドン認識の構造的基礎
Alan Brown1, Sichen Shao1, Jason Murray1
1MRC-LMB, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
Nature
|August 7, 2015
まとめ
ユカリオット放出因子1 (eRF1) は,3つのストップコドンをすべて認識します. 新しい冷凍電子顕微鏡構造は,eRF1がリボソームRNAを使ってメッセンジャーRNAを圧縮し,正確なストップコドン差別を可能にすることを明らかにしています.
科学分野:
- 分子生物学
- 構造生物学
- 遺伝学
背景:
- タンパク質合成の終結は,リボソームのA位にあるストップコドン (UAA,UAG,UGA) の認識に依存する.
- 細菌は別々の放出因子を使用し,真核生物は単一の全能放出因子 (eRF1) を使用する.
- eRF1がストップコドンとセンスのコドンを区別するメカニズムは不明である.
研究 の 目的:
- eRF1によるエウカリオットストップコドン認識の分子基礎を解明する.
- eRF1,リボソーム,ストップコドンの間の構造的相互作用を決定する.
主な方法:
- 高解像度構造 (3.5-3.8 Å) を得るために,冷凍電子顕微鏡 (冷凍EM) が使用された.
- 哺乳類のリボソーム複合体をERF1と3つのストップコドンごとに分析した.
主要な成果:
- eRF1結合は,18SリボソームRNAの構造変化を誘導し,ヌクレオチドA1825を反転させます.
- このヌクレオチドは第2と第3のストップコドンベースに積み重ねられ,メッセンジャーRNAを圧縮します.
- rRNAとeRF1残基間の水素結合ネットワークは,さらにストップコドン認識を安定させる.
結論:
- この研究は,eukaryotic ストップコドン特異性を eRF1 がどのように達成するかの分子枠組みを提供します.
- eRF1は,メッセンジャーRNAの圧縮を促進するために,tRNAの選択に関与するリボソームRNA核酸体を利用する.
- 発見は,正典と早めの翻訳終了メカニズムへの洞察を提供します.
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