光駆動ナトリウムポンプの5秒からミリ秒の構造変化
Petr Skopintsev1, David Ehrenberg2, Tobias Weinert1
1Laboratory of Biomolecular Research, Biology and Chemistry Division, Paul Scherrer Institut, Villigen, Switzerland.
Nature
|June 6, 2020
まとめ
研究者はシリアル結晶学を用いてクロキノバクター・エイカストス・ロドプシン2 (KR2) のナトリウムポンプの光サイクルを視覚化しました. 構造的な変化によって 光が介在するナトリウムが 膜を横切る事が出来るのです
科学分野:
- バイオ物理学
- 構造生物学
- オプトジェネティクス
背景:
- Krokinobacter eikastus rhodopsin 2 (KR2) のような 光駆動ナトリウムポンプは 微生物のエネルギー変換と 価値ある光遺伝的ツールに不可欠です
- 以前の研究では,KR2の静止状態構造を解明しましたが,活性ナトリウム輸送を可能にするダイナミックな構造の変化は不明でした.
研究 の 目的:
- 光周期中のKR2ナトリウムポンプの時間分解構造ダイナミクスを解明する.
- 光によるナトリウム転移の 分子メカニズムを理解する
主な方法:
- スイスのX線自由電子レーザーの連続X線結晶学.
- ポンプ探査の遅延 (フェムト秒からミリ秒) の範囲で時間解像度データ収集
- 構造データとスペクトロスコーピ的方法と量子化学計算の統合
主要な成果:
- 高解像度のスナップショットはKR2の構造変化を フェムト秒からミリ秒に捉えました
- 網膜のイソメリゼーションと結合ポケットの再配置は,ナノ秒で発生しました.
- 静電ゲートはマイクロ秒で開けられ 網膜の近くで一時的なナトリウム結合が起こります
- 第2の潜在的なナトリウム結合部位は,細胞外出口の近くで20ミリ秒で特定されました.
結論:
- この研究は,光によるナトリウム輸送の ダイナミックなプロセスに先例のない 分子洞察を提供します.
- KR2の機能を支配する重要な構造的中間要素とタイミングを特定した.
- 活性カチオン輸送メカニズムと光遺伝的ツール操作の理解を進める.
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