自由エネルギーパルブレーションによるヒトイニシアチブ因子eIF4EによるmRNAキャップ結合の熱力学分析
Cristiano R W Guimarães1, David J Kopecky, Jeff Mihalic
1Department of Molecular Structure, Amgen, Inc., 1120 Veterans Boulevard, South San Francisco, California 94080, USA.
Journal of the American Chemical Society
|November 21, 2009
まとめ
ユカリオットmRNAの7メチルグアノシンキャップは,翻訳開始因子eIF4Eの結合を強化する. この改善された親和性は,有利なヴァン・デル・ワールズ相互作用とメチル基からの溶解の減少によるものです.
科学分野:
- 分子生物学は分子生物学である.
- バイオフィジックス 生物物理学
- コンピューティング・ケミストリー
背景:
- ユカリオットmRNAの翻訳開始は,7メチルグアナシンキャップ (m7GpppX) に依存しています.
- ユカリオットのトランスレーション開始因子4E (eIF4E) は,mRNAキャップ構造と直接相互作用する.
- 以前の研究では,m7GTPは非メチル化GTPよりもeIF4Eに好意的に結合することを示しています.
研究 の 目的:
- eIF4Eが様々なキャップ・アナログに結合する過程を熱力学的に分析する.
- eIF4E/m7GpppX capの相互作用における7メチルグループの特定の役割を明らかにする.
主な方法:
- モンテカルロ (MC) シミュレーション.
- 自由エネルギー波動 (FEP) の計算.
- キャップアナログ (m7GTP,GTP,プロトン化されたGTP,m7DTP,DTP) の結合自由エネルギーの熱力学分析.
主要な成果:
- GTP上のN(7) メチル群は,GTPと比較して,結合の自由エネルギー獲得の半分に寄与する.
- Trp166との有利なヴァン・デル・ワールスの相互作用と,N(7) 原子の溶解の減少が観察されました.
- 残りの親近性獲得は,グアニン部分の陽性電荷と関連しており,Trp56とTrp102.2とのカチオン-π相互作用を容易にしています.
結論:
- 7メチルグループは,ステリックおよび電子効果を通じて,eIF4Eの結合親和性を著しく高めます.
- ヴァン・デル・ワールズ相互作用と変異した溶解の両方がメチルグループの効果に貢献します.
- 静電相互作用,特にカチオン-π相互作用は,複合体をさらに安定させます.
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