Na+独立のアミノ酸トランスポーターの構造とメカニズム
Paul L Shaffer1, April Goehring, Aruna Shankaranarayanan
1Vollum Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA.
Science (New York, N.Y.)
|July 18, 2009
まとめ
アミノ酸トランスポーターApcTの結晶構造は,陽子結合輸送のメカニズムを示しています. 他のトランスポーターのナトリウムイオン部位に似たライシン残留物は,このプロセスの鍵です.
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
- メンブレーン輸送 メンブレーン輸送
背景:
- アミノ酸,ポリアミン,およびオルガノケーション (APC) トランスポーターは,栄養素の吸収,廃棄物の除去,および細胞のバランスの維持に関与する重要な二次トランスポーターです.
- APCトランスポーター機能の構造的基礎を理解することは,細胞輸送機構の解読に不可欠です.
研究 の 目的:
- 陽子結合アミノ酸トランスポーターであるApcTのアポ状態の高解像度結晶構造を決定する.
- ApcTの輸送メカニズムと,他の二次輸送業者との関係を明らかにする.
主な方法:
- X線結晶学を用いて,アポ-ApcTの結晶構造を2.35アングストームの解像度で得られた.
- 生物情報分析と構造的比較を使用して,重要な機能的残留物と保存された輸送原理を特定しました.
主要な成果:
- apo-ApcTの2.35アングストロームの結晶構造は, LeuTトランスポーターと構造的に類似した12トランスメブランヘリックスバンドルを明らかにしています.
- ライシン残留物 (Lys-158) は,LeuTのNa2イオン結合部位と同様の位置で特定され,陽子結合における役割を示唆しました.
- 構造は,閉塞状態または輸送後の状態の特徴である内向きの形状を呈しています.
結論:
- ApcTの構造は,陽子結合アミノ酸輸送のメカニズムに関する重要な洞察を提供します.
- リジン-158は,陽子の転位に中心的な役割を果たし,関連するトランスポーターにおけるナトリウムイオンの役割を機能的に模倣することが提案されています.
- この研究は,陽子とナトリウム結合二次輸送体間の保存されたメカニズム原理を強調しています.
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