アクティブサイト改造は,SUMO E1のチオエステル結合形成に伴います
Shaun K Olsen1, Allan D Capili, Xuequan Lu
1Structural Biology, Sloan-Kettering Institute, New York, New York 10065, USA.
Nature
|February 19, 2010
まとめ
この研究は,SUMOタンパク質のE1酵素活性化背後の構造的メカニズムを明らかにしています. 結晶構造は,E1酵素が触媒ドメインを改造して,重要なチオエステル結合を形成する方法を示しています.
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
- 分子生物学は分子生物学である.
背景:
- E1酵素は,2段階のプロセスを経て,ユビキチン (Ub) とユビキチン類似タンパク質 (Ubl) を活性化するために不可欠です.
- このプロセスは,カーボキシ末端アデニル化と,触媒的なシステイン残留物とのチオエステル結合形成を伴う.
- E1酵素機能におけるこれらの重要な中間物質の構造的基礎は,ほとんど不明のままである.
研究 の 目的:
- SUMO (Small Ubiquitin-like Modifier) タンパク質のE1酵素媒介活性化に伴う構造的メカニズムを解明する.
- アデニル化およびチオエステル結合形成の中間物質に関する高解像度の構造的洞察を提供する.
主な方法:
- ヒトのSUMO E1.1.の構造を決定するために,X線結晶学を用いた.
- SUMOアデニラートと四面体中間類の複合体を2.45と2.6 Åの解像度で分析した.
- 観察された構造変化の機能的意義を検証するために,変異分析と生化学分析が行われました.
主要な成果:
- 結晶構造は,チオエステル結合形成中にE1触媒型システインドメインのダイナミックな位置転換を明らかにします.
- アデニレーション後にCysドメインの有意な130度回転が起こり, ATP.Mgへのサイドチェーンコンタクトの解放によって引き起こされます.
- 触媒作用に関与するヘリクやループを含む主要な構造要素は,アデニレーションからチオエステル結合形成への移行を容易にするために,実質的な改造を受けています.
結論:
- この研究は,SUMO活性化中のE1酵素の動的構成変化に関する最初の構造的証拠を提供します.
- これらの発見は,E1酵素がドメインの回転と構造の再構築を通じてアデニレーションからチオエステル結合形成にどのように切り替わるかを説明します.
- 特定されたメカニズムは,異なるE1酵素にわたって保存される可能性があり,Ub/Ubl活性化のための一般的なモデルを提供します.
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