リボヌクレオチド還元酵素内のコンフォーメーション・ダイナミック・ラジカル・トランスファー
Brandon L Greene1, Alexander T Taguchi2, JoAnne Stubbe2
1Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
Journal of the American Chemical Society
|October 18, 2017
まとめ
リボヌクレオチド還元酵素は,核酸還元のためにラジカル移転を使用する. この研究では タンパク質の柔軟性により 酵素の機能に不可欠な 素粒子の移動が速くなります
科学分野:
- 生物化学
- 酵素学
- タンパク質ダイナミクス
背景:
- リボヌクレオチド還元酵素 (RNR) はDNA合成に不可欠な酵素である.
- クラス1aのRNRは,システインチル基を含む根幹移転 (RT) メカニズムを使用します.
- ラジカル転送は,α2:β2サブユニットインターフェイスで,陽子結合電子転送 (PCET) により発生する.
研究 の 目的:
- RNRの基質移転における構造動態の役割を調査する.
- E. coli class 1a RNRのR411A変異体における根幹移転のメカニズムを記述する.
- サブユニットインターフェースにおける 基質移転の運動を決定する.
主な方法:
- サイト指向型変異 (R411A)
- 3アミノチロシン (NH2Y) をラジカル・トラップとして設置するアンバー・コドン抑制.
- HYSCOREのスペクトロスコープで 閉じ込められたラジカル状態を研究する
- 運動研究のための光化学的激素生成.
主要な成果:
- Y731のH結合を妨害するR411A変異は,酵素活性を維持し,形状の柔軟性を示しています.
- R411Aの変異体Y731は,H結合をダイナミックにリフォームし,急性移転の拡散を可能にします.
- R411A変異体では速度が増加する.
- Y731の形状の変化は,n−μsの時間スケールで発生し,触媒速度より速い.
結論:
- ティロシン残基の適合性の柔軟性は,RNRにおける効率的な基質移転に不可欠である.
- ダイナミックなH結合リフォームは,PCET経路に沿ってラジカル伝播を促進します.
- 酵素の動態は,タンパク質の動態と基質輸送の相互作用によって調節される.
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