クラスCのラジカルS-アデノシル-l-メチオニンのチアゾルメチル移転酵素のメカニズム
Zhengan Zhang1,2, Nilkamal Mahanta1,3, Graham A Hudson1
1Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
Journal of the American Chemical Society
|December 1, 2017
まとめ
この研究は,チオペプチド抗生物質のバイオシンセシスに不可欠なC級ラジカルS-アデノシルメチオニン (rSAM) メチルトランスフェラーゼ,TbtIのメカニズムを明らかにしています. 2つのSAM分子と異なる水素転送ステップを含む新しいメチル化経路を発見した.
科学分野:
- 生物化学
- 有機化学
- 分子生物学
背景:
- ラジカルS-アデノシルメチオニン (rSAM) メチルトランスファーゼは,活性化されていない炭素センターのメチル化を触媒化する.
- 4つのrSAMメチルトランスファーゼのクラスが特定されていますが,クラスB-Dのメカニズムはほとんど不明です.
- これらのメカニズムを理解することは 複雑な生物合成経路の解明に不可欠です
研究 の 目的:
- クラスCrSAMメチルトランスファーゼTbtIの詳細なメカニズムを調査する.
- チオペプチド抗生物質チオムラシンの生物合成におけるTbtIの役割を解明する.
- 翻訳後の成熟時にCys由来チアゾールのメチル化を特徴付ける.
主な方法:
- TbtI媒介メチル化の製品分析
- S-アデノシルメチオニン (SAM) を用いた同位体標識研究
- 水素転送経路と溶媒交換の分析
主要な成果:
- TbtIはチアゾール前駆体のCメチル化のために2つのSAM分子を必要とします.
- 1つのSAMは5'-デオキシアデノシンに,2つ目はS-アデノシル-l-ホモシステイン (SAH) に変換される.
- SAM2のメチル群からSAM1への明確な水素移転と,チアゾールβ位置の水素移転が観察されました.
結論:
- クラスCのrSAMメチルトランスファーゼのための新しいメチル化メカニズムが提案されています.
- このメカニズムは,他の特徴づけられたrSAMメチルトランスファーゼと著しく異なる.
- この発見はチオペプチド抗生物質の 生合成に関する重要な洞察をもたらします
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