ABCトランスポーター結合タンパク質複合体BtuCD-BtuFの構造の非対称性
Rikki N Hvorup1, Birke A Goetz, Martina Niederer
1Institute of Molecular Biology and Biophysics, ETH Zurich, HPK D14.3, 8093 Zurich, Switzerland.
Science (New York, N.Y.)
|August 4, 2007
まとめ
BtuCD-F複合体の構造は,Escherichia coliによるビタミンB12輸送における重要な構造変化を明らかにしています. この構造は,アデノシン三酸塩結合カセットトランスポーターメカニズムにおける転位後の中間体を表す可能性があります.
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
- 分子微生物学 分子微生物学
背景:
- BtuCDはアデノシン三リン酸結合カセット (ABC) トランスポーターで,Escherichia coli.でビタミンB12の吸収に不可欠です.
- ビタミンB12は,周回プラズマ結合タンパク質BtuFからBtuCD経由で細胞質に転位する.
研究 の 目的:
- BtuCD-F複合体によるビタミンB12転位の構造的メカニズムを解明する.
- BtuCD-Fトランスポーターの輸送サイクル中の構造変化を調査する.
主な方法:
- BtuCD-F複合体の2.6アングストーム構造を決定するX線結晶学.
- プロテオリポソーム内のスピンラベル付システイン変異体の電子パラマグネティック共振 (EPR) スペクトロスコーピー.
主要な成果:
- BtuCD-F構造は,個々のBtuCDとBtuF構造と比較して,実質的な形状の変化を示しています.
- ビタミンB12がBtuF結合ポケットから大きく移動し,BtuCサブユニットの特徴的な形状が観察されました.
- 転位経路は,決定された構造の膜の両側で閉まっていることが判明しました.
- EPRデータは,結晶構造の形状を裏付け,転移後の状態を示唆しています.
結論:
- BtuCD-F複合体の決定された構造は,ABCトランスポーターの構成動態に関する洞察を提供します.
- この発見は,BtuCD-F構造が,輸送サイクルをスナップショットにすることで,転移後の中間物質を表すことを示唆しています.
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