エシェリキア大腸菌からの翻訳開始複合体の冷凍-EM構造
Gregory S Allen1, Andrey Zavialov, Richard Gursky
1Howard Hughes Medical Institute, Health Research, Inc. at the Wadsworth Center, Albany, New York 12201, USA.
Cell
|June 7, 2005
まとめ
研究者は,バクテリアの翻訳開始複合体を,クリョー-EMを用いて視覚化しました. 彼らは,イニシアーションファクター2 (IF2) がリボソームとfMet-tRNAに結合する様子を観察し,タンパク質合成に不可欠な新しい形状を明らかにしました.
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
- 微生物学 微生物学とは
背景:
- バクテリアの翻訳開始は,70Sリボソームと複数の開始因子を含む複雑なプロセスです.
- これらのコンポーネントの正確な構造的配置を理解することは,タンパク質合成の調節を解読する鍵です.
研究 の 目的:
- GDPNP.で停止したバクテリアの翻訳開始複合体 (IC) の高解像度構造を決定する.
- IC内のイニシアチブファクター2 (IF2) の役割と構成を解明する.
主な方法:
- E. coli 70S リボソームの浄化と翻訳開始因子.
- GDPNPを使用した安定したICのインビトロ組立.
- クリオ電子顕微鏡 (cryo-EM) で,ICの3D再構築を図る.
主要な成果:
- 凍結-EM再構築では,IF2*GDPNPが70Sリボソームのインターサブユニット裂け目に位置していることを明らかにしました.
- IF2は,以前に決定された結晶構造とは異なる新しい形状を採用した.
- IF2のC末端ドメインはfMet-tRNA ((fMet)) と相互作用し,それをP部位に独自に指向した.
- IF2のGTP結合ドメインは,50SサブユニットのGTPアソシエイトドメインと関連しており,伸縮因子に似ています.
結論:
- この研究は,細菌の翻訳開始に関する前例のない構造的洞察を提供します.
- IF2は,ICを安定させ,独特の構造変化によってイニシアターtRNAの位置づけに重要な役割を果たします.
- IF1,IF3,およびリボソームタンパク質などの他の要因の局所化も実証されました.
関連する概念動画
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02:33Initiation of Translation
Initiating translation is complex because it involves multiple molecules. Initiator tRNA, ribosomal subunits, and eukaryotic initiation factors (eIFs) are all required to assemble on the initiation codon of mRNA. This process consists of several steps that are mediated by different eIFs.
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
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