停止した転写複合体の構造 Pol II-DSIF-NELF
Seychelle M Vos1, Lucas Farnung1, Henning Urlaub2,3
1Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany.
Nature
|August 24, 2018
まとめ
研究者は,冷凍EMを用いて,一時停止したRNAポリメラーゼII (Pol II) を視覚化しました. 負の伸縮因子 (NELF) はPol IIの移動性を抑制し,転写の伸縮を防止し,遺伝子調節を一時停止する.
科学分野:
- 分子生物学
- 構造生物学
- 遺伝子規制
背景:
- メタゾーン遺伝子の調節には,しばしばRNAポリメラーゼII (Pol II) がプロモーター近接領域で一時停止することが含まれます.
- タンパク質複合体であるDRB感受性誘導因子 (DSIF) とネガティブ伸縮因子 (NELF) は,一時停止したPol IIを安定させる.
- 遺伝子発現制御の解読には,Pol IIの停止の分子メカニズムを理解することが重要です.
研究 の 目的:
- 高解像度冷凍電子顕微鏡 (cryo-EM) の構造を決定する.
- NELFとDSIFがPol IIを停止状態に保つための分子相互作用とメカニズムを解明する.
- プロモーター近接遺伝子調節におけるNELFの役割を理解するための構造的基礎を提供すること.
主な方法:
- 凍結電子顕微鏡 (cryo-EM) を用いて,一時停止した転写延長複合体の構造を決定した.
- この複合体にはSus scrofa Pol IIとHomo sapiens DSIFとNELFが含まれていた.
- 構造は3.2 Åの解像度で解像した.
主要な成果:
- 凍結-EM構造は,核酸三酸基板結合を阻害する,傾いたDNA-RNAハイブリッドを明らかにした.
- NELFはポリメラーゼファネルを結合し,移動ポリメラーゼモジュールを橋渡しし,トリガーループに接触し,Pol IIの移動性を制限することが観察されました.
- NELFは,転写延長因子IIS (TFIIS) の結合を阻害し,DSIFとRNAと相互作用する柔軟な"触角"を有することが示された.
結論:
- この研究は,停滞したRNAポリメラーゼII状態の構造特性を定義する.
- この発見は,NELFがPol IIを抑制し,一時的な放出を防ぐ方法について分子的な説明を提供します.
- この構造的な洞察は,遺伝子発現を調節するNELFの機能を理解するために不可欠です.
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