テトラヒメナリボジームの保存されていない配列の変異により,活性と特異性が増加します
B Young1, D Herschlag, T R Cech
1Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Colorado, Boulder 80309-0215.
Cell
|November 29, 1991
まとめ
テトラヒメナリボ酵素のJ1/2領域の変異は,RNAの分裂効率と特異性を高めます. これらの改善は,RNAの結合親和性が低下し,効率的な触媒作用のために基板の位置を最適化することで生じる.
科学分野:
- 分子生物学は分子生物学である.
- バイオケミストリー バイオケミストリー
- RNAのカタリシス
背景:
- グループIのイントロンであるテトラヒメナ・リボ酵素は,RNA基板結合部位と触媒核を結びつけるためにJ1/2領域を利用する.
- J1/2配列はグループIのイントロンに保たれていないが,その変更はリボジーム活性に大きく影響する.
研究 の 目的:
- J1/2領域の小さな挿入または削除がリボエンザイム触媒RNA分裂の周回数と配列特異性にどのように影響するか調査する.
- J1/2配列の変異によって生じるリボエンザイム活性の増加のメカニズム的根拠を解明する.
主な方法:
- 速度定数を測定するために個々の反応ステップの運動分析.
- 野生型と変異したテトラヒメナ・リボジームの比較.
主要な成果:
- J1/2領域の変異は,ターンオーバー数とシーケンスの特異性を劇的に向上させた.
- これらの改善は,逆説的に,RNA基板に対する afinity の低下と関連していました.
- J1/2配列は,最適の三次相互作用と割裂部位選択のためにRNA基板を位置づけることが判明しました.
結論:
- 保存されていないJ1/2配列は,直接の触媒強化ではなく,基板の位置づけに影響することによって,リボジーム機能を最適化するのに重要な役割を果たします.
- 野生型のリボ酵素は生物学的に適応している一方で,J1/2の変異は,複数のターンオーバーシナリオでの制限を克服することができます.
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