単一のRecBCDヘリカーゼ/ヌクレアゼ分子によるChi配列認識とDNA転位

K M Dohoney¹, J Gelles

¹Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454-9110, USA.

Nature

|February 24, 2001

まとめ

RecBCD酵素というものです.

科学分野:

分子生物学は分子生物学である.
バイオケミストリーバイオケミストリー
遺伝学遺伝学とは

背景:

Escherichia coliにおける再結合DNA修復は,ヘリカーゼとヌクレアゼ活動を持つ複雑な酵素であるRecBCDタンパク質に依存しています.
RecBCDタンパク質は,DNA配列"チ"を認識し,その分裂活動を変化させ,再結合を促進します.
以前のモデルでは,活動変化を説明するために"チ"のRecDサブユニット放出を示唆していました.

研究の目的:

単一の RecBCD 分子の転位機構を調査する.
"チ"配列が単一分子レベルで RecBCD 酵素の活性をどのように変化させるかを解明する.

主な方法:

結合粒子光顕微鏡を用いて,単一のRecBCD分子を追跡した.
顕微鏡のポリシュチレンビーズは,可視化のためにRecDサブユニットに接続されました.
酵素の転位速度と"チ"配列の行動が正確に測定されました.

主要な成果:

単一の RecBCD 分子は,一定の速度で単方向転位を示します.
"チ"配列は,重要なビーズ解離を引き起こさないため,RecDサブユニット放出がないことを示しています.
"チー"の酵素活性変化は,RecDサブユニットシフトなしに起こります.

結論:

RecBCDトランスロケーションは,そのDNA解速度と一致する一方的なプロセスです.
"Chi"シーケンスでは,RecBCDサブユニットのエジェクションではなく,コンフォメーションスイッチを通じてRecBCDの活動を変更します.
この研究は,RecBCD.によるDNA修復調節のメカニズム的基礎に関する新しい洞察を提供します.

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