バクテリアの外膜内のリガンド特異の輸送タンパク質によってゲートチャネルが形成される
1Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226.
Science (New York, N.Y.)
|October 16, 1992
まとめ
変異した鉄性エンテロバクチン受容体 (FepA) は,TonB.から独立して,受動的チャネルを形成する. これは,FepAがゲートされたポリンであり,TonBがバクテリアのリガンド輸送のゲートキーパーとして機能することを示唆しています.
科学分野:
- 微生物学 微生物学とは
- 構造生物学 構造生物学とは
- バイオケミストリー バイオケミストリー
背景:
- 鉄性エンテロバクチン受容体 (FepA) は,グラム陰性細菌の重要な外膜タンパク質であり,鉄-シドロフォア複合体の高親和性吸収を担当する.
- FepAはトランスポーターとして機能し,付属タンパク質TonBと相互作用して,リガンドの侵入を促進します.
研究 の 目的:
- リガンド輸送におけるFepAの構造的および機能的役割を調査する.
- FepAがTonBと相互作用し,栄養素の吸収を媒介するメカニズムを決定する.
主な方法:
- FepAの細胞表面リガンド結合ペプチドを削除するために,サイト指向型変異遺伝子が使用されました.
- その結果生じた変異FepAタンパク質の輸送能力とチャネル特性を分析した.
- 付属タンパク質TonBに対するFepA媒介輸送の依存度を評価した.
主要な成果:
- FepAの削除変異体は,高親和性の吸収能力を失いました.
- これらの変異FepAタンパク質は,細菌の外膜に非特異的,受動的なチャネルを形成した.
- 変異FepAの受動的チャネル活動は,ネイティブ受容体とは異なり,TonBとは独立していました.
結論:
- この発見は,FepAがゲートされたポリンとして機能し,TonBがゲートキーパーとして機能することを示唆しています.
- TonBの役割は,リガンドのFepAチャネルへの侵入を容易にし,特定の輸送を可能にすることです.
- このゲートド・ポリンメカニズムは,リガンド特異的輸送のためのTonB依存の外膜受容体の中で保存されている可能性が高い.
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