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ATP結合状態と基板結合状態に閉じ込められたヒトABCG2変異体の冷凍-EM構造
Ioannis Manolaridis1, Scott M Jackson1, Nicholas M I Taylor2,3
1Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, Switzerland.
Nature
|November 9, 2018
まとめ
この研究は,ABCG2トランスポーター機能の構造的メカニズムを明らかにします. 高解像度の冷凍-EM構造は,ATP結合が細胞膜を介して基板の転移をどのように誘導するかを示しています.
科学分野:
- 生物化学
- 構造生物学
- 分子生物学
背景:
- ABCG2 (ATP結合カセットサブファミリーGメンバー2) は,細胞防御と薬物薬動学に関与する重要なトランスポータータンパク質です.
- ABCG2の構造と抑制は知られているが,その基質認識と輸送メカニズムは不明である.
研究 の 目的:
- ヒトのABCG2による基質認識とATP駆動輸送の分子メカニズムを解明する.
- ABCG2の高解像度冷凍電子顕微鏡 (cryo-EM) 構造を重要な機能状態で提示する.
主な方法:
- 高解像度冷凍電子顕微鏡 (cryo-EM) を使用して,機能的なABCG2変異体 (ABCG2EQ) の構造を決定した.
- エストロン-3硫酸塩 (E1S) は,転位前の状態と転位後の状態を捉えるためのモデル基板として使用されました.
- 構造的な発見を検証するために,変異性およびin vitro輸送およびATPaseアッセイが行われました.
主要な成果:
- クリオ- EM構造は,ABCG2の異なる基板結合 (転移前) とATP結合 (転移後) 状態を明らかにした.
- 基板結合腔は中部にあり,転移前の状態で細胞質に面しており,単一のE1S分子を収容しています.
- ATP結合は構造変化を誘導し,内腔を崩壊させ,ドメインのシフトとNBDの方向性の変化を含む基板の流出のために外腔を開く.
結論:
- ABCG2はATP結合を利用して,基質転位のための構造変化を誘導する.
- レウシン"プラグ"を含む特定の残留物は,基板の認識と基板と阻害剤の区別に極めて重要です.
- この発見は,ABCG2がエフフルスポンプとしてどのように機能し,薬剤の有効性と異種生物からの保護に影響を及ぼすかについてのメカニズム的な洞察を提供します.
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