システインメチル化により,NF-κB活性化におけるユビキチン鎖感知が妨げられます
Li Zhang1, Xiaojun Ding, Jixin Cui
1Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
Nature
|December 14, 2011
まとめ
Enteropathogenic Escherichia coli NleEは,NF-κBシグナル伝達に不可欠なTAB2およびTAB3タンパク質をメチル化することによって,宿主免疫反応を阻害する. このバクテリアエフェクターは,鍵となるウビキチン鎖結合を無効化し,感染中に先天性免疫を乱します.
科学分野:
- 微生物学 微生物学とは
- 免疫学 免疫学とは
- 分子生物学は分子生物学である.
背景:
- 核因子カッパB (NF-κB) 信号伝達は,微生物病原体に対する先天的免疫に不可欠である.
- バクテリア感染,特に腸病原性Escherichia coliによって,NF-κB信号伝達経路を阻害することがあります.
- 細菌が感染中にNF-κBの活性化におけるユビキチン鎖のシグナル伝達特異性を調節する正確なメカニズムは,ほとんど未知のままである.
研究 の 目的:
- 細菌の病原体がNF-κB活性化におけるユビキチン鎖のシグナル伝達特異性をどのように調節するかを調査する.
- 感染中にNF-κBシグナル伝達を阻害するバクテリアの要因と宿主標的を特定する.
- 腸病原性Escherichia coliが宿主NF-κB反応を抑制する分子メカニズムを解明する.
主な方法:
- エステロパトゲン性Escherichia coli型III分泌エフェクターNleEと宿主タンパク質TAB2およびTAB3の相互作用を調査しました.
- S-アデノシル-l-メチオニンを用いてNleEの酵素活性を特徴づけ,その基板特異性を特定しました.
- NleE媒介メチレーションがTAB2およびTAB3機能およびNF-κB活性化に与える影響を評価するために,タンパク質の断片化,子宮外発現,およびサイト誘導性変異を生成した.
主要な成果:
- Enteropathogenic Escherichia coli NleEは,NF-κBシグナル伝達における重要なユビキチン鎖感知タンパク質であるヒトのTAB2とTAB3を直接無効化する.
- NleEはS-アデノシル-l-メチオニン依存メチルトランスフェラーゼ活性を持ち,特にTAB2とTAB3のNpl4亜鉛指 (NZF) ドメインのシステイン残基をメチル化する.
- TAB2-NZFとTAB3-NZFドメインのメチル化により,亜鉛イオンが失われ,ユビキチン鎖結合活性が失われ,NF-κBシグナル伝達が阻害されます.
- 宿主細胞におけるTAB2およびTAB3のNleE媒介メチル化により,それらのユビキチン鎖結合能力が低下する.
- TAB3 NZFドメインをメチル化不敏感の変異体に置き換えると,NF-κBの活性化がNleEに抵抗するようになった.
結論:
- 腸病原性エシェリキア大腸菌からのバクテリアエフェクターNleEは,宿主NF-κBの先天性免疫シグナリングを妨害するために新しいメチル化戦略を採用しています.
- 細菌メチルトランスファーゼによる亜鉛指システイン残留物の改変は,NF-κBを含む真核細胞経路の調節のための保存されたメカニズムを表しています.
- ホストのユビキチネーション機構のこの細菌の操作を理解することは,ホスト-病原体相互作用と潜在的な治療標的の洞察を提供します.
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