単一のアスパルテートは,ヘッジホッグの自動処理における2つの触媒ステップを調整する
Jian Xie, Timothy Owen1, Ke Xia
1Department of Chemistry, Binghamton University, State University of New York , 4400 Vestal Parkway East, Binghamton, New York 13902, United States.
Journal of the American Chemical Society
|August 17, 2016
まとめ
ヘッジホッグ (Hh) の重要なアスパルテート残留物 (D46) は,コレステロールの修正に不可欠なタンパク質の自己処理をシグナルする. この残留物は2つの触媒のステップを結合し,効率的なHh信号経路の活性化を保証します.
科学分野:
- 生物化学
- 分子生物学
- 細胞シグナリング
背景:
- ヘッジホッグ (Hh) 信号は,コレステロール改変されたHhリガンドによって開始されます.
- Hhリガンド生成には,Hh前駆タンパク質の自己処理が含まれています.
- 効率的なHhシグナル伝達には,N-Sアシルシフトと,コレステロール化のためのトランスエステル化ステップの結合が必要である.
研究 の 目的:
- Hh自動処理領域における保存されたアスパルテート残基 (D46) の役割を調査する.
- D46がHh自己処理とコレステロール化の触媒的ステップを調整するメカニズムを解明する.
主な方法:
- Hh前駆体タンパク質のD46残基のサイト指向型変異.
- 核磁気共振 (NMR) スペクトロスコーピーは,D46のpKaを決定する.
- Hhコレステロールと自己処理の効率を測定する.
主要な成果:
- 変異はD46が非本来の自己処理を抑制し,コレステロールのトランスエステル化に不可欠であることを明らかにした.
- NMRデータによると,D46は触媒性システインとの水素結合によりpKa (5.6) が上昇している.
- D46N変異はHhコレステロール化を廃止し,D46のプロトン化と脱プロトン化の両方の重要性を示した.
結論:
- アスパルテート残基D46は,Hh自処理の重要な調整剤として作用する.
- D46のプロトンシャトルメカニズムは,N-Sアシルシフトとトランスエステル化ステップを機械的にリンクしています.
- このD46による調整は,Hhコレステロールと,その後の信号伝達に不可欠である.
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