宿主防御を抑制するシゲラエフェクターによるGBPのユビキチン化と分解
Peng Li1,2, Wei Jiang2, Qin Yu2
1Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, National Institute of Biological Sciences, Beijing, 102206, China.
Nature
|November 17, 2017
まとめ
シゲッラ・フレックスネリ菌は,IpaH9.8エフェクタを使用して,ガニラート結合タンパク質 (GBP) を分解することによって,免疫防御を回避する. このプロセスを妨害することで GBPは細菌の増殖を抑制し,宿主と病原体の相互作用における重要なメカニズムを明らかにします
科学分野:
- 免疫学
- 微生物学
- 細胞生物学
背景:
- インターフェロン誘導性ガニラート結合タンパク質 (GBP) は,細胞自律の抗菌免疫に不可欠です.
- Shigella flexneriは,細菌のユビキチン・リガゼで,機能が十分に理解されていない侵入性プラズミド抗原Hs (IpaHs) を含む,III型分泌システムエフェクターを使用しています.
研究 の 目的:
- シゲッラ・フレックスネリがガニラート結合タンパク質によって媒介される宿主の防御を回避するメカニズムを調査する.
- 感染中に宿主GBPを標的とし,劣化させる特定の細菌因子を特定する.
主な方法:
- hGBP1の分解に抵抗する変異体を特定するために,S.flexneriでトランスポゾンスクリーンを実施した.
- バイオケミカルアッセイを用いて,IpaH9.8によるhGBP1のLys48関連ユビキチン化とタンパク質分解を証明した.
- 野生型と変異性S.flexneriを持つマウスモデルと,さまざまなGBP欠陥を持つマウスで,細菌の複製と宿主の生存を評価した.
主要な成果:
- S. flexneriのエフェクターIpaH9.8がヒトのガニラート結合タンパク質-1 (hGBP1) の迅速なタンパク質分解に起因することを確認した.
- IpaH9.8が細胞質に複数のGBPを標的にし,S.flexneriの複製を促進し,宿主死亡を引き起こすことが示された.
- IPAH9.8機能またはGBP結合の障害により,GBPが細胞内細菌に転移し,複製を阻害し,宿主の生存を向上させることが示された.
結論:
- S. flexneriのエフェクターIpaH9.8は,主要な宿主防御タンパク質を劣化させ,GBP媒介の免疫を積極的に破壊する.
- GBPは細胞内細菌感染を制御する上で重要な役割を果たし,病原体の生存と毒性を保つために,細菌エフェクターによる脱出は不可欠である.
- IpaH9.8-GBPの相互作用は,抗菌免疫におけるGBPの機能を研究するための新しいシステムを提供します.
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