翻訳リボソームに結合したE. coli信号認識粒子の構造

Christiane Schaffitzel¹, Miro Oswald, Imre Berger

¹ETH Zurich, Institute for Molecular Biology and Biophysics, HPK Building, Schafmattstrasse 20, 8093 Zurich, Switzerland.

Nature

|November 7, 2006

まとめ

プロカリオットの信号認識粒子 (SRP) 構造は,どのようにタンパク質を内膜にターゲットにするかを明らかにします. この複合体は,翻訳リボソームと新生鎖を結合し,タンパク質の転位を促進します.

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
微生物学微生物学とは

背景:

信号認識粒子 (SRP) 経路は,プロカリオットの細胞膜にタンパク質を標的にするために重要である.
SRPは,翻訳リボソームと新生ポリペプチド鎖を結合して,それらを正しい膜挿入装置に導きます.

研究の目的:

翻訳リボソームとの複合体におけるEscherichia coli SRPの高解像度構造を決定する.
SRP媒介タンパク質ターゲティングと膜挿入の構造的基礎を解明する.

主な方法:

構造データを得るために,冷凍電子顕微鏡 (cryo-EM) と単粒子の再構築を用いた.
バクテリアのリボソームとSRPコンポーネントの既知の高解像度構造をEM密度マップに組み込む.

主要な成果:

E. coli SRP-リボソーム-新生鎖複合体の16 Å解像度構造が得られ,標的複合体を明らかにした.
リボソーム上のSRPの構成や,複合形成に関わる領域に関する構造的な洞察が得られた.
シグナルシーケンス認識および高親和性SRP結合におけるコンフォーム変化が特定されました.

結論:

決定された構造は,受容体結合に備えたSRP標的化複合体の詳細な見方を提供します.
この発見は,SRP媒介の共翻訳タンパク質が細菌内膜を標的とするメカニズムについての洞察を提供します.
この研究は,タンパク質転位中のSRP-リボソーム相互作用のダイナミクスを理解するための基礎を築いています.

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