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病原体は,アルギニンによる宿主死亡受容体シグナリングをブロックし,死亡ドメインのGlcNAcylationを誘導する
1College of Biological Sciences, China Agricultural University, Beijing 100094, China.
Nature
|August 20, 2013
まとめ
Enteropathogenic Escherichia coliは,死領域を改変し,NF-κB,アポプトシス,そしてネクロプトシスのような重要な細胞シグナル伝達経路をブロックすることによって,宿主の免疫反応を抑制するためにNleBを使用します. N-アセチルグルコサミントランスファーゼの活性を含むこの細菌のメカニズムは,感染に不可欠です.
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:
- 腫瘍死滅因子 (TNF) 信号伝達は,免疫ホメオスタシス,炎症,細胞死において極めて重要です.
- TNFR受容体 (TNFR) 家族のメンバーは,TNFR1とFASのように,死領域を通してこれらの信号を媒介します.
- これらのドメインは,TRADDやFADDなどのアダプタータンパク質と相互作用して,下流信号伝達を誘発する.
研究 の 目的:
- 腸病原性Escherichia coli (EPEC) が宿主の免疫信号伝達を抑制するメカニズムを特定する.
- 死亡受容体経路の調節におけるEPEC型III分泌系エフェクターNleBの役割を調査する.
- NleBの酵素活性と宿主細胞死と炎症への影響を特徴づける.
主な方法:
- NleBの酵素活性を決定する生化学的分析.
- サイト・ディレクテッド・ミュータジェネシスにより,NleBの主要残留物を特定し,死亡領域をターゲットにします.
- NF-κBシグナル伝達,アポプトーシス,およびネクロプトーシスを評価するための細胞ベースのアッセイ.
- バクテリアのコロニー化におけるNleBの役割を評価するためのインビボ感染モデル.
主要な成果:
- NleBは,N-アセチルグルコサミン (GlcNAc) 転送酶活性を持ち,TRADD,FADD,RIPK1,TNFR1.1を含むタンパク質の死亡領域に保存されたアルギニンを修正する.
- このGlcNAcylationは死亡ドメインを無効化し,重要なタンパク質-タンパク質相互作用とTNFR1複合体やDISCのようなシグナル伝達複合体の組み立てを防ぐ.
- TNF,NF-κB,アポプトーシス,およびネクロプトーシス信号伝達の障害は,EPECに感染した細胞で観察されました.
- NleBのGlcNAc移転酵素の活動は,マウスモデルでのEPECコロニー化に不可欠でした.
結論:
- EPECからのNleBは,死領域の新しい翻訳後の改変 (GlcNAcylation) を通して,宿主TNFRとFASのシグナル伝達経路を直接抑制します.
- このバクテリアの戦略は,炎症や細胞死を含む宿主の免疫反応に効果的に抵抗します.
- NleBのアルギニンGlcNAcトランスファーゼの活性性の発見は,細菌の病原性の新しいメカニズムと,評価されていないタンパク質改変の形態を明らかにしています.
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