2アングストームの解像度でイオン輸送中のバクテリアホドプシンにおける構造変化

H Luecke¹, B Schobert, H T Richter

¹Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA. hudel@uci.edu

Science (New York, N.Y.)

|October 9, 1999

まとめ

バクテリアホドプシンの構造的な洞察

科学分野:

バイオケミストリーバイオケミストリー
構造生物学構造生物学とは
膜タンパク質膜タンパク質

背景:

バクテリアホドプシン (Bacteriorhodopsin) は,細胞のエネルギー生成に不可欠な光駆動型陽子ポンプである.
そのメカニズムを理解するには,陽子の転位サイクル中の構造変化を分析する必要があります.
ミュータントAspp96Asnは,このサイクルにおける特定のステップを研究するためのモデルを提供します.

研究の目的:

Asp96Asnバクテリアホドプシン変異体におけるM光介質の構造的基礎を解明する.
光周期中の陽子の放出とエネルギー保存の基礎となる分子再編成を理解するために.

主な方法:

結晶構造を決定するために,X線結晶学を用いた.
ミュータントとそのMフォトインターミディアートの高解像度構造 (1.8および2.0アングストーム) が得られた.
密度図の分析により,原子レベルの構造変化が明らかになった.

主要な成果:

M光間介質の構造は,Asp85への陽子の移転と,外側に放出することを明らかにします.
網膜の13-cis,15-antiへのフォトアイソメリゼーションは,サイドチェーンの重要な移転を誘導します.
水素結合ネットワークと水分子の広範な再配置により,pKa値が変化する.

結論:

決定された構造は,バクテリアホドプシンにおける遅いM状態の詳細な見方を提供します.
構造の変化は,エネルギー保存と方向性プロトン転移を説明する.
この研究は,光駆動プロトンポンプのメカニズムに関する重要な洞察を提供します.

キーワード:

非プログラム的なものです.

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