ライシン結合状態に閉じ込められたシトクロームcのコンパクトな構造:ループの再折り畳みと適合スイッチの機能的影響
Jeanine F Amacher1, Fangfang Zhong2, George P Lisi2
1†Department of Biochemistry, Geisel School of Medicine, Hanover, New Hampshire 03755, United States.
Journal of the American Chemical Society
|June 4, 2015
まとめ
シトクロームc (cytc) のアルカリ的形態は構造変化を起こし,LysがMet80.0を代用する. この構造的シフトは,その過酸化酵素の活性性を高め,アポトーシスの役割をサポートします.
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
- 細胞生物学 細胞生物学
背景:
- サイトクロームc (cyt c) は酸化リン酸化とアポトーシスで機能します.
- cytcのアルカリ的形態では,LysがMet80を代用し,ヘム鉄の結合が変化する.
- リンガンドスイッチング時の細胞の形状の変化は完全に理解されていません.
研究 の 目的:
- リンス結合に切り替わる際の細胞の構造的再編成を解明する.
- この構造変化が過酸化酵素の活性に及ぼす機能的影響を調査する.
- cyt c.におけるライス結合の熱力学的基礎を提供するため.
主な方法:
- Lys73結合型サイトcの高解像度結晶構造の決定.
- Cys78の化学誘導により,溶液を模倣する.
- 酵素活性アッセイと,モデルタンパク質を使った生体物理実験.
主要な成果:
- Lys73結合型細胞のコンパクトな構造が決定され,ヘム環境の変化が顕著であった.
- ヘム・コーディネーション・ループはβヘアピンに折り畳まれ,ヘムポケットの体積が増加します.
- Cys78-derivatizedミミックはペロキシダースの活性が強化され,アポトーシスにおけるLys-ligated cytcの役割をサポートしました.
結論:
- Lys-ligated cytcは,拡大したヘムポケットを持つ独特でコンパクトな構造を示しています.
- この構造的適応は,心臓リピンの相互作用を促進し,アポトーシス中の過酸化酵素の活性を強化します.
- 熱力学的な研究は,特定のタンパク質の支架の乱れの下で,Lys結合への切り替えを説明します.
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