バクテリアのHsp70を通るポリペプチドの流れ:DnaKは,新生鎖を支える誘発因子と協力し合います
1Max-Planck-Institut für Biochemie, Department of Cellular Biochemistry, Martinsried, Germany.
Cell
|June 25, 1999
まとめ
主要なE. coli Hsp70,DnaKは,新生ポリペプチドと結合することで,デノボタンパク質の折り畳みを支援する. DnaKとトリガーファクター遺伝子の併せ削除は致死性であり,タンパク質の折り畳みにおける重複する機能を示している.
科学分野:
- 分子生物学は分子生物学である.
- タンパク質の折りたたみ
- バクテリアの生理学
背景:
- ストレスのない条件下での新しいタンパク質の折りたたみにおけるEscherichia coli Hsp70 (DnaK) の役割は不明である.
- トリガーファクターは,E. coliのリボソーム関連チャペロンであり,早期のタンパク質折りたたみにおける役割が知られている.
研究 の 目的:
- E. coli の de novo タンパク質の折りたたみ過程で,新生ポリペプチドを護衛する DnaK の関与を調査する.
- 細胞活性を維持する際のDnaKとトリガーファクターの機能的関係と潜在的重なりを明らかにする.
主な方法:
- DnaKと新生ポリペプチドの相互作用を検出するために免疫プレシピテーションアッセイが利用されました.
- DnaKとトリガーファクター遺伝子の単一および二重削除変異を生成した.
- 生成された変異体の正常な条件下でのバクテリアの成長と生存能力を評価した.
主要な成果:
- DnaKは,非ストレスの条件下で,さまざまな新合成タンパク質,特に30 kDa以上のタンパク質と一時的に結合することが判明しました.
- トリガーファクター遺伝子の削除により,DnaKと新生ポリペプチドの関連性が著しく増加 (倍増) しました.
- DnaKとトリガーファクター遺伝子の同時削除は,標準的な成長条件下でE. coliの致死性を引き起こした.
結論:
- DnaKは,ストレスがない場合でも,新生ポリペプチドのデノボ折り畳みに重要な役割を果たします.
- DnaKとトリガーファクターは,タンパク質の折りたたみにおける重要な部分的に重複する機能を有する.
- 観察された重複する機能は,以前に指摘されたE. coliのDnaKまたはトリガーファクターの喪失に対する耐性を説明する.
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