T7RNAポリメラーゼにおける転位とヘリケース活性に関する構造的メカニズム
Y Whitney Yin1, Thomas A Steitz
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Cell
|March 16, 2004
まとめ
RNAポリメラーゼは分子モーターとして作用する. ピロホスファートの放出によって引き起こされるその構造の変化は,転写中にDNA転位と鎖分離を可能にします.
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
- バイオケミストリー バイオケミストリー
背景:
- RNAポリメラーゼは,転写に不可欠な分子モーターです.
- そのメカニズムを理解するには,異なる機能状態に関する詳細な構造的な洞察が必要です.
研究 の 目的:
- 核酸添加および転位中のRNAポリメラーゼ機能の構造的基礎を解明する.
- DNA鎖の分離と転位における酵素構成の役割を調査する.
主な方法:
- X線結晶学を用いて,ファグT7RNAポリメラーゼの構造を決定した.
- 伸縮相基板とプレトランスロケーション製品複合体の構造が得られた.
主要な成果:
- ヌクレオチド添加サイクル中に2つの異なる酵素構成が特定されました.
- 5ヘリクスのサブドメインは,入ってくる核酸三酸 (NTP) または産物パイロフォスファート (PPi) によって安定された異なる方向性を採用します.
- NTPまたはPPiの欠如は,転位とDNA鎖の分離に関連するコンフォームを安定させます.
結論:
- 製品PPi解離はRNAポリメラーゼの構造変化を誘発する.
- この形状の変化は,転位とDNA鎖の分離を可能にするために非常に重要です.
- RNAポリメラーゼは,異なった構造状態を利用して,化学エネルギーとトランスクリプションにおける機械的な作業を組み合わせます.
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