ラジカルS-Adenosyl-l-Methionine Oxygenase DarEは,部分的に異地化されたトリプトファンCを介してエーテル結合を形成する
Bach X Nguyen1, Melissa M Bollmeyer2, Hai Nguyen1
1Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, United States.
Journal of the American Chemical Society
|January 23, 2026
まとめ
ダロバクチンは,グラム陰性細菌に対する強力な抗生物質で,ラジカル酵素 DarEによって形成されたユニークなエーテルクロスリンクを使用します. この研究で明らかになったのは,
科学分野:
- 生物化学
- 自然製品の生物合成
- 抗生物質の研究
背景:
- ダロバクチンは,グリム陰性病原体に対する有意な活性を持つリボソーム合成および翻訳後の改変ペプチド (RiPP) である.
- 抗生物質の有効性は2つのトリプトファン残基間のエーテルクロスリンクによって強化されたユニークなβ鎖構造に依存しています.
- このエーテル結合は,未修正のトリプトファン残留物と分子酸素を用いた,過激なS-アデノシル-l-メチオニン (SAM) 酵素DarEによって形成され,他の自然産物エーテル結合とは機械的に異なる.
研究 の 目的:
- ダロバクチンエーテルクロスリンクを形成するDarE酵素のほとんど未知の触媒機構を解明する.
- 基質媒介によるO原子の組み込みとエーテル結合形成プロセスに関与する主要な中間物質を特定し,特徴づけること.
主な方法:
- 同位体ラベル DarAとそのW3変種を使用した.
- 酵素活性を研究するために運動分析を用いた.
- 電子パラマグネティック共振 (EPR),電子核二重共振 (ENDOR),超精細結合 (HYSCORE) を含む,高度なスペクトロスコピーを適用した.
主要な成果:
- トリプトファンのCβ位置で重要な中間基 W3-Cβ•を成功裏に検出し,特徴づけました.
- DarAのW3変種を含む反応において,類似した根性種が観察された.
- DarEは,分子酸素 (O2) と反応する中介物質W3-Cβを介してエーテルクロスリンク形成を触媒とする直接的な証拠を提供した.
結論:
- この発見は,RiPPの生物合成にO原子を組み込むための前例のない根幹媒介メカニズムを示しています.
- この研究は,DarEがドロバクチンの特徴的なエーテルクロスリンクをどのように形成するかについての直接的なメカニズム的な洞察を提供します.
- 特徴づけられた中間基は,この新しい生物合成戦略を理解するための鍵です.
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