無結合および転写RNAポリメラーゼIIIの分子構造
Niklas A Hoffmann1, Arjen J Jakobi1,2, María Moreno-Morcillo1
1European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
Nature
|November 26, 2015
まとめ
研究者はRNAポリメラーゼIII (Pol III) の構造を視覚化し,そのサブユニット組織と構成を明らかにした. これらの発見は,Pol IIIが重要な小さなRNAをどのように転写するかについての新しい洞察を提供します.
科学分野:
- 分子生物学
- 構造生物学
- 生物化学
背景:
- RNAポリメラーゼIII (Pol III) は,トランスファーRNA,リボソーム5SRNA,スプレイスソームU6小核RNAを含む必須小型の構造RNAを転写する.
- 重要な役割にもかかわらず,Pol IIIは構造的に最も特徴のないエウカリオットRNAポリメラーゼである.
研究 の 目的:
- Saccharomyces cerevisiae Pol III酵素とその延長複合体の高解像度構造を決定する.
- 17亜単位のPolIII酵素の原子モデルを作りました
- Pol IIIの特異的な転写メカニズムに関する新しい洞察を得るために
主な方法:
- クリオ電子顕微鏡 (cryo-EM) を用いて,2つの形状 (4.6と4.7の解像度) でPol IIIの延長複合体 (3.9 Å解像度) とApo Pol IIIの構造を得ました.
- これらの再構築により,Pol IIIの17つのサブユニットの原子模型が作られました.
主要な成果:
- C82-C34-C31ヘトロトリマーの正確な方向性を明らかにします.
- 非テンプレートDNA鎖の隣接するC53-C37ヘテロダイマーの位置が解明され,転写終結におけるその役割が強調された.
- アポポルIIIの構造は,異なる茎の向きとクラップの形状 (閉じたり開いたり) を示しています.
結論:
- この研究は,真核RNAポリメラーゼIIIに関する前例のない構造的な洞察を提供します.
- 発見は,小さなRNAのPol III特異的転写の構造的基礎を明らかにする.
- 構造は,Pol IIIが小さな転写標的にどのように適応するかを明らかにします.
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