AMP-PNP結合ビタミンB12トランスポーターBtuCD-Fの構造
Vladimir M Korkhov1, Samantha A Mireku, Kaspar P Locher
1Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland.
Nature
|September 25, 2012
まとめ
E. coli のビタミンB12吸収に不可欠なATP結合カセット (ABC) トランスポーターBtuCDは,新しい輸送機構を明らかにしています. 構造と機能の研究は,他のABCトランスポーターとは異なるユニークな中間状態と環静止運動を明らかにします.
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
- 微生物学 微生物学とは
背景:
- ATP結合カセット (ABC) トランスポーターBtuCDは,Escherichia coli.でビタミンB12の吸収を促進する.
- 以前の構造研究はアポ状態を明らかにしたが,輸送機構は明らかにしなかった.
研究 の 目的:
- 機能的な中間状態の構造を決定することによって,BtuCDの輸送機構を明らかにする.
主な方法:
- AMP-PNPに結合したBtuCD-BtuF複合体の3.5 Åの結晶構造の決定.
- 放射性リガンド捕獲試験.
- エンジニアリング・ジスルファイド・クロスリンクと機能分析.
主要な成果:
- BtuCサブユニットの新しい形状は,密閉されたサイトプラズマゲートを明らかにし,閉じられた空洞を形成しました.
- 膜の真ん中にあるこの穴は,ビタミンB12を収納しています.
- BtuCD-F複合体は,AMP-PNPの存在下でビタミンB12と結合する.
結論:
- この発見は,ビタミンB12の予期せぬ環静脈輸送メカニズムを示唆している.
- このメカニズムは,他のABCトランスポーターで観察されたものとは大きく異なる.
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