ATP誘発のヘリケースリップは,高度に調整されたサブユニットを明らかにします
Bo Sun1, Daniel S Johnson, Gayatri Patel
1Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
Nature
|September 20, 2011
まとめ
バクテリオファージT7ヘリケーゼは,dTTPだけでなく,ATPを使用してDNAを解き放ち,協調されたサブユニット活動を明らかにします. この協調は,複製と修復のメカニズムに不可欠なプロセス性DNA解き放たれを保証する.
科学分野:
- バイオケミストリー バイオケミストリー
- 分子生物学は分子生物学である.
- 酵素学 酵素学とは
背景:
- ヘリカーゼは,複製,修復,再結合中のDNA鎖分離に不可欠な酵素です.
- バクテリオファージT7遺伝子プロダクト4は,モデルヘクサメリカヘリケーズであり,以前は,主に二重鎖DNA (dsDNA) の解き放たれのためにdTTPを使用すると考えられていた.
研究 の 目的:
- トランスロケーション中のT7ヘリケーゼのサブユニット間の化学力学的活動とDNA結合の調整を調査する.
- T7ヘリケースの解き放たれとプロセシビティにおけるATPとdTTPの役割を決定する.
主な方法:
- 単一分子アプローチを用いて,ヘリカーゼ解ダイナミクスをモニタリングした.
- ATP,dTTP,およびヌクレオチド混合物の存在下での解速度とプロセシビティを分析した.
- 核酸結合と水解の動態を研究した.
主要な成果:
- T7ヘリケーゼは,dTTPよりも速い速度で,ATPでdSDNAを効率的に解き放ちます.
- ATP誘発の解き放たれは,スリップイベントを含む歯パターンを示し,プロセシビティの障害を示した.
- 漸進性は,ニュクレオチド濃度に対する協力的依存を示し,独立した行動よりも協調されたサブユニット機能を示唆した.
結論:
- T7ヘリケーゼサブユニットは,彼らの化学力学的活動とDNA結合を調整し,独立したサブユニット機能のモデルに矛盾しています.
- 一度に1つのサブユニットのみが核酸を受容し,他のサブユニットがDNA相互作用のために核酸結合のままであるモデルは,観察されたプロセシビティを説明します.
- このサブユニット協調機構は,他の環状ヘリカーゼに保存され,DNA解の調節に関する洞察を提供します.
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