バクテリアのフェリチンDps,AのDNA媒介による酸化の特徴
Anna R Arnold1, Andy Zhou1, Jacqueline K Barton1
1Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States.
Journal of the American Chemical Society
|August 30, 2016
まとめ
Dpsタンパク質は 細菌のDNAを酸化ストレスから守ります グアニンとトリプトファンによって促進されるDNA電荷輸送は,細菌の生存に不可欠なDps鉄部位の効率的な酸化を可能にします.
科学分野:
- 生物化学
- 分子生物学
- スペクトロスコーピー
背景:
- Dpsタンパク質は,細菌の生存と毒性に影響を与える酸化ストレスからDNAを保護するために不可欠な細菌フェリチンです.
- Dpsの鉄部位の酸化は,直接接触またはDNA電荷輸送 (CT) により,DNA塩基対のπスタックを通して電子と穴の輸送を含むメカニズムによって起こる.
研究 の 目的:
- 鉄質のDpsタンパク質のDNA媒介による酸化のメカニズムを光譜で調査する.
- Dps酸化中の電子移転を促進するDNA塩基とタンパク質残留物の役割を解明する.
主な方法:
- X帯電子パラマグネティック共振 (EPR) スペクトロスコピーは,Dps酸化をモニターするために使用されました.
- DNAの光酸化は,ルテニウム光酸化剤とフラッシュ・キッチ技術を用いて誘導された.
- 実験では合成DNAポリマーであるpoly (dGdC) 2とpoly (dAdT) 2とW52A Dps変異体を使用した.
主要な成果:
- Dpsをpoly ((dGdC) 2) で照射すると,g=4. 3でEPR信号が発生し,単核高スピンFe ((III)) 部位が形成されたことを示した.
- poly(dAdT) 2で代用すると,Dpsの酸化率が大幅に低下し,グアニンラジカル中間物質がプロセスを促進することを示唆しています.
- W52A Dps変異体はFe (III) 信号の形成に顕著な欠陥を示し,トリプトファン残基W52を電子転送中間物質として含有した.
結論:
- 特にグアニンを含むDNA電荷輸送は,Dpsの鉄部位を酸化する効率的なメカニズムである.
- 保存されたトリプトファン残基W52は,DNA媒介によるDps酸化における重要な電子転送ホッピング中間体として作用する.
- W52A変異は,Dpsの機能をインビトロで低下させ,また,酸化ストレス下での細菌の生存をインビヴォで低下させる.
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