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Xenopus laevis as a Model to Identify Translation Impairment
Published on: September 27, 2015
タンパク質合成の開始におけるヒト翻訳因子eIF3の構造的役割
Bunpote Siridechadilok1, Christopher S Fraser, Richard J Hall
1Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
まとめ
タンパク質合成は,リボソームサブユニットの組み立てに不可欠な大きな複合体であるイニシアチブファクターeIF3に依存しています. この研究では,eIF3が,5'-capまたは内部リボソームエントリーサイト (IRES) を通してメッセンジャーRNA (mRNA) と相互作用して,イニシアーションを容易にすることを明らかにしています.
科学分野:
- 分子生物学は分子生物学である.
- 構造生物学 構造生物学とは
- ウイルス学 ウイルス学 ウイルス学
背景:
- 哺乳類の細胞におけるタンパク質合成の開始は,複雑なプロセスである.
- イニシエーション因子eIF3 (約750 kDa複合体) は,このプロセスにおいて重要な役割を果たしています.
- eIF3は,40SリボソームサブユニットのメッセンジャーRNA (mRNA) への組み立てを調節する.
研究 の 目的:
- eIF3が40SリボソームサブユニットへのmRNA結合を媒介する構造的メカニズムを解明する.
- eIF3のキャップ依存および内部リボソームエントリーサイト (IRES) 依存のイニシアーション経路との相互作用を調査する.
主な方法:
- eIF3.3の構造を視覚化するために,冷凍電子顕微鏡 (cryo-EM) の再構築を用いた.
- 詳細な分子モデリングを使用して,eIF3および関連因子を40Sリボソームサブユニットに配置しました.
主要な成果:
- クリオ・エム検査では,eIF3が5葉の粒子であることを明らかにした.
- eIF3は,同じドメインを使って,C型肝炎ウイルス (HCV) のIRESRNAと5キャップ結合複合体eIF4Fと相互作用します.
- 構造モデリングにより,eIF3は,eIF4FとHCV IRESの相互作用の両方に対して同様の方法で,mRNAを40Sリボソーム出口部位の近くに置いていることが示されました.
結論:
- eIF3は,タンパク質合成の開始のためのmRNAの採用を容易にするために,保存された構造的メカニズムを使用しています.
- このメカニズムは,内部リボソームエントリーサイト (IRES) を利用するものを含む,異なるmRNA型に適応できます.
- eIF3の役割を理解することで,ウイルスのRNA翻訳と一般的なタンパク質合成の調節に関する洞察が得られます.
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