Ste5スキャフォールドは,Fus3 MAPキナーゼを触媒的に解き放ち,活性化のために交配シグナルを送信する
Matthew Good1, Grace Tang, Julie Singleton
1Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
Cell
|March 24, 2009
まとめ
Ste5スキャフォルドタンパク質は,酵母が交配経路をシグナル化する上で極めて重要です. 新たに特定されたSte5ドメインは,Fus3 MAPKを触媒的に活性化し,経路の特異性を説明します.
科学分野:
- 細胞の信号伝達経路は,
- 信号伝導の分子メカニズム
- 酵母遺伝学と分子生物学
背景:
- Ste5のような基板タンパク質は,キナーゼと基板を結びつけることでシグナル伝達を促進することが知られている.
- イーストの交配経路は,シグナル伝達のためにミトゲン活性化タンパク質キナーゼ (MAPK) であるFus3に依存しています.
- 以前のモデルでは,Ste5へのFus3結合がSte7.5による活性化に不可欠であると示唆されていた.
研究 の 目的:
- Ste5が酵母の交配経路内でFus3の活性化を誘導するメカニズムを調査する.
- Ste5の既知のFus3結合部位がFus3シグナル伝達に不可欠であるかどうかを判断する.
- MAPKの活性化を調節するSte5の新たな機能を特定する.
主な方法:
- MAPKのシグナル伝達経路の in vitro 再構成.
- ステー5.5のFus3結合部位を破壊するために,サイト指向型変異を起こします.
- Ste5ドメインの構造的特徴.
- Ste7.7によるFus3とKss1のリン酸化率 (kcat) を測定する酵素測定法.
主要な成果:
- Ste5上の以前に特定されたFus3結合部位は,Fus3シグナル伝達には欠かせない.
- Fus3は,関連するMAPK Kss1.1とは異なり,その活性化キナーゼ,Ste7にとって,インビトロでは貧弱な基板である.
- Ste5内の新しいドメインが特定され,構造的に特徴づけられました.
- このSte5ドメインは,特にSte7媒介のFus3リン酸化の触媒効率 (kcat) を向上させるが,Ste7媒介のKss1リン酸化はそうではない.
結論:
- Fus3の活性化におけるSte5の役割は,単純な脚架を超えて広がり,触媒的な解鎖機能を持っています.
- このSte5ドメイン媒介の活性化メカニズムは,交配経路におけるFus3の選択的活性化を説明する.
- 発見は,MAPKシグナル伝達における経路特異性を保証する洗練された規制メカニズムを明らかにしています.
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