RNAなしのRNase P:ヒトミトコンドリアのtRNA処理酵素の識別と機能的再構成
Johann Holzmann1, Peter Frank, Esther Löffler
1Center for Anatomy & Cell Biology, Medical University of Vienna, 1090 Vienna, Austria.
Cell
|November 6, 2008
まとめ
人間のミトコンドリアのRNase Pは,tRNAの成熟に不可欠であり,タンパク質のみの酵素であり,リボジームによって触媒化されていません. この発見は,ミトコンドリアが既存のタンパク質を再利用し,祖先のRNA成分を失うことを明らかにしています.
科学分野:
- バイオケミストリー バイオケミストリー
- 分子生物学は分子生物学である.
- 遺伝学 遺伝学とは
背景:
- 転送RNA (tRNA) は,タンパク質合成に不可欠であり,当初は前体分子として合成された.
- RNase P酵素は,成熟のためのプレ-tRNAから5'リーダー配列を除去する不可欠なエンドヌクレアゼです.
- 以前は,特徴づけられたすべてのRNase P酵素は,リボ酵素として機能するRNA成分を含んでいることが知られていた.
研究 の 目的:
- 人間のミトコンドリアのRNase P.の成分を特定する.
- 人間のミトコンドリアのRNase P.の酵素活性を再構成し,特徴づけること.
- 人間のミトコンドリアのRNase P触媒にRNAが必要かどうかを判断する.
主な方法:
- ヒトミトコンドリアのRNase P成分を特定するために,組み合わせた浄化とプロテオミクスのアプローチを使用しました.
- 3つの浄化された再結合タンパク質を用いて酵素活性を再構成した.
- 再構成された酵素の触媒機構と成分要件を特徴づけた.
主要な成果:
- 人間のミトコンドリアのRNase Pは,3つのタンパク質成分から再構成された.
- 再構成された酵素は,tRNA 5'端処理活性を示した.
- 触媒はタンパク質ベースのもので,RNA分子とは独立していることが確認されました.
- この酵素は,tRNAメチルトランスフェラーゼ,短鎖脱水素酵素/還元酵素ファミリーのメンバー,および新しいタンパク質で構成されています.
結論:
- 人間のミトコンドリアのRNase Pはタンパク質のみの酵素であり,普遍的なリボ酵素モデルに挑戦しています.
- ミトコンドリアは,既存のタンパク質機構を利用して,新しいRNA独立RNase Pを進化させた.
- この発見は,動物のミトコンドリアにおける祖先のRNA成分の喪失を示唆し,タンパク質によって機能的な置き換えが行われている.
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