光駆動型イオンポンプの主要な転送ステップ バクテリアホドプシン: ダイナミックな核極化強化の魔法の角度回転による不可逆的なUターン
Qing Zhe Ni1, Thach V Can1, Eugenio Daviso1,2
1Department of Chemistry and Francis Bitter Magnet Laboratory , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States.
Journal of the American Chemical Society
|March 1, 2018
まとめ
バクテリアホドプシン (bR) のプライマリ陽子伝搬は,DNP強化のNMRを用いて明確にされる. Thr89はシフ基質陽子をAsp85に伝達し,ヘリックス運動と染色体の変化を伴う.
科学分野:
- バイオ物理学
- 構造生物学
- スペクトロスコーピー
背景:
- バクテリアホドプシン (bR) は 細胞エネルギーに不可欠な 光駆動型陽子ポンプです
- bR内の陽子伝達のメカニズム,特に最初のステップは,まだ完全に理解されていません.
- bRの陽子伝達経路を理解することは 生物学的システムにおけるエネルギー伝達を解読する鍵です
研究 の 目的:
- バクテリアホドプシンにおける原発陽子の移動の分子経路を解明する.
- 主要な陽子伝送中間体 (L,Mo,N状態) 中の活性部位の構造的動態を調査する.
- 特定のアミノ酸残留物と構造要素が,陽子の移転を促進する役割を特定する.
主な方法:
- ダイナミック・ニュクリア・ポラライゼーション (DNP) 強化のマジック・アングル・スピニング (MAS) 核磁気共振 (NMR) スペクトロスコーピー.
- 15SB) -1H,13C,そして15N-13Cの相関実験を利用した.
- 高解像度構造の洞察のために 75倍信号の強化を達成しました.
主要な成果:
- シーフ塩基 (SB) がアルコールの水素結合を受け取り,
- 陽子の移転前にThr89に近づくことが示されました.
- CとGのヘリケアは 陽子の移動前に収束し その後は分岐し 染色体の回転を伴います
結論:
- トレオニン89 (Thr89) は,シフ塩基 (SB) からアスパルテート85 (Asp85) にプロトンを転送する中介物として作用する.
- 陽子伝達経路の形成には,ヘリックスCとヘリックスGの近接とクロモフォアのトルションを含むダイナミックな構造的再配置が含まれます.
- これらの発見は,バクテリアホドプシンにおける陽子転移の分子機構に関する重要な洞察を提供します.
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