複素体におけるDNAポリメラーゼの独立かつストキャスティックな作用
James E Graham1, Kenneth J Marians2, Stephen C Kowalczykowski1
1Department of Microbiology and Molecular Genetics and Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
Cell
|June 17, 2017
まとめ
複素体内のDNAポリメラーゼは独立して動作し,協調した合成を必要としない. このダイナミックなプロセスは 厳格な同期ではなく ストキャスティックな休止とレートのスイッチングを通して DNAの完全な複製を保証します
科学分野:
- 分子生物学
- 遺伝学
- 生物化学
背景:
- DNA複製を担うレピソームは,以前は,先端と後端のDNAポリメラーゼの間の厳密な調整を必要とすると考えられていた.
- この調整は,複製中に新たに合成されたDNA鎖の重要なギャップを防ぐために必要と考えられた.
研究 の 目的:
- 単一の複素体内の先端と後端DNAポリメラーゼの機能的調整を調査する.
- 複製中のDNA合成速度とポリメラーゼ-ヘリカーゼの相互作用を制御するダイナミックなメカニズムを解明する.
主な方法:
- DNAポリメラーゼの活性を観察するためにリアルタイム単分子分析を使用した.
- 個々のDNAポリメラーゼの軌跡と合成速度を in situ で追跡した.
主要な成果:
- リードストランドとラギングストランドのDNAポリメラーゼは,同じレプリソーム内で独立して機能する.
- 個々のポリメラーゼは,合成速度のストキャスティックな切り替えと明確な停止イベントを示します.
- ヘリケーゼの速度低下 (∼80%) を含む自律メカニズムにより,パウスの後のポリメラーゼ再結合が可能である.
結論:
- DNA複製は,継続的に破壊され,リフォームされた複素体コンタクトを持つ運動的に不連続なプロセスです.
- 複素体構成要素のストキャスティックな行動は,鎖合成の直接的な調整なしに完全なDNA複製を保証する.
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