原型陽子チャネルにおける複数の時間スケールの輸送関連タンパク質構成動力学と水動力学:固体NMRからの洞察
Venkata S Mandala1, Martin D Gelenter1, Mei Hong1
1Department of Chemistry, Massachusetts Institute of Technology , 170 Albany Street, Cambridge, Massachusetts 02139, United States.
Journal of the American Chemical Society
|January 6, 2018
まとめ
インフルエンザM2タンパク質
科学分野:
- バイオ物理学
- 構造生物学
- 膜タンパク質
背景:
- インフルエンザM2タンパク質は,ウイルスの侵入に不可欠な四重陽子チャンネルを形成します.
- 前回の研究で ヒスティディンが 陽子の伝導に 関わっていることが分かりましたが 伝導速度が遅いのは解明できませんでした
- M2タンパク質は形状の可塑性を示し,ダイナミクスの影響機能を示唆しています.
研究 の 目的:
- 固体NMRを用いてM2タンパク質のW41F変異を調査する.
- 陽子伝導率と分子ダイナミクスの違いを解明する.
- タンパク質と水のダイナミクスを 陽子伝導機構に繋げます
主な方法:
- M2タンパク質 W41F変異体に対する固体NMRスペクトロスコーピー.
- 形状を特定するためのC化学シフト分析
- H T2 リラクゼーション測定で,水の動態を測る.
- 2D相関スペクトロスコーピーは,相互変換率を決定する.
主要な成果:
- pHに依存する2つの異なるテトラメア構造を特定した.
- 輸送時間スケールに関連した ~400 s-1での構成間の相互変換を観察した.
- 運河の水はpHに関係なく ナノ秒の動きを示します
- 水の移動,ヒスティジンの移転,および形状の変化のための明確な時間スケールを特定した.
結論:
- プロトンの伝導は,グラット・ホッピング (ピコ秒-ナノ秒の水運動) を含む.
- ヒスティジンのサイドチェーンダイナミクス (マイクロ秒) は,水-ヒスティジンの陽子の移転を容易にする.
- 速度を制限するステップは,4ヘリックスバンドル運動 (ミリ秒) で,陽子の流れを制御します.
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