胆酸トランスポーターとHBV受容体NTCPの構造
Jinta Asami1, Kanako Terakado Kimura2, Yoko Fujita-Fujiharu3,4,5
1Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
Nature
|May 17, 2022
まとめ
B型肝炎ウイルス (HBV) は,宿主細胞の受容体と結合するために,大型包膜グリコタンパク質 (LHBs) を利用する. この研究は,NTCP経由でのHBV侵入の構造的基礎を明らかにし,ウイルスと宿主の相互作用を理解するための枠組みを提供します.
科学分野:
- 構造生物学
- ウイルス学
- ヘパトロジー
背景:
- B型肝炎ウイルス (HBV) の慢性的な感染は,世界中で2億9千万人を襲い,肝硬変や肝がんを引き起こします.
- HBVが肝細胞に侵入するには,ウイルスの大型包膜グリコタンパク質 (LHBs) と宿主受容体であるナトリウムタウロコラート共輸送ポリペプチド (NTCP) の相互作用が必要である.
- HBVとNTCPの相互作用の基礎となる正確な分子メカニズムは,まだ十分に理解されていません.
研究 の 目的:
- HBVと宿主細胞のエントリー受容体であるNTCPとの相互作用の構造的基礎を解明する.
- NTCPによるナトリウム依存性胆酸輸送の仕組みを理解する.
- HBVに対する新しい抗ウイルス戦略の開発のための構造的枠組みを提供すること.
主な方法:
- クリオ電子顕微鏡 (cryo-EM) を用いて,ヒト,牛,ラットのNTCPの構造をアポおよびプレS1結合状態で決定した.
- 提案された結合モードと機能的影響を検証するために,変異と輸送測定が行われました.
- 構造分析と生化学データを統合して,NTCPにおけるHBV感受性変異を解釈した.
主要な成果:
- Cryo-EM構造は,NTCPに膜を横断するトンネルを明らかにし,基板輸送経路を示唆しました.
- LHBs preS1領域に結合するヒトのNTCPの構造は,preS1とNTCP基板がトンネルの細胞外開口で同じ結合部位を争っていることを示した.
- preS1-NTCPの相互作用の分析は,HBV耐性を授与する自然に発生する変異に関するメカニズム的洞察を提供した.
結論:
- この研究では,NTCPの高解像度構造が提供され,その輸送メカニズムとHBVとの相互作用が詳細に説明されています.
- NTCPによるHBV認識の構造的枠組みが確立され,ウイルスの侵入の分子基盤が明らかにされています.
- これらの発見は,胆酸輸送のメカニズムを理解し,標的型HBV治療の道を開きます.
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