ジャーナル: EMBO J / 年: 2010 タイトル: tmRNA-SmpB: a journey to the centre of the bacterial ribosome. 著者: Félix Weis / Patrick Bron / Emmanuel Giudice / Jean-Paul Rolland / Daniel Thomas / Brice Felden / Reynald Gillet / 要旨: Ribosomes mediate protein synthesis by decoding the information carried by messenger RNAs (mRNAs) and catalysing peptide bond formation between amino acids. When bacterial ribosomes stall on ...Ribosomes mediate protein synthesis by decoding the information carried by messenger RNAs (mRNAs) and catalysing peptide bond formation between amino acids. When bacterial ribosomes stall on incomplete messages, the trans-translation quality control mechanism is activated by the transfer-messenger RNA bound to small protein B (tmRNA-SmpB ribonucleoprotein complex). Trans-translation liberates the stalled ribosomes and triggers degradation of the incomplete proteins. Here, we present the cryo-electron microscopy structures of tmRNA-SmpB accommodated or translocated into stalled ribosomes. Two atomic models for each state are proposed. This study reveals how tmRNA-SmpB crosses the ribosome and how, as the problematic mRNA is ejected, the tmRNA resume codon is placed onto the ribosomal decoding site by new contacts between SmpB and the nucleotides upstream of the tag-encoding sequence. This provides a structural basis for the transit of the large tmRNA-SmpB complex through the ribosome and for the means by which the tmRNA internal frame is set for translation to resume.
エネルギーフィルター名称: In-column Omega Filter エネルギーフィルター 上限: 20 eV / エネルギーフィルター 下限: 0 eV
放射
プロトコル: SINGLE WAVELENGTH / 単色(M)・ラウエ(L): M / 散乱光タイプ: x-ray
放射波長
相対比: 1
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解析
EMソフトウェア
ID
名称
バージョン
カテゴリ
1
MDFF
モデルフィッティング
2
UCSF Chimera
モデルフィッティング
3
IMAGIC
5
3次元再構成
CTF補正
詳細: Each particle
対称性
点対称性: C1 (非対称)
3次元再構成
解像度: 13 Å / 解像度の算出法: FSC 0.5 CUT-OFF / 粒子像の数: 70761 / 対称性のタイプ: POINT
原子モデル構築
ID
プロトコル
空間
Target criteria
詳細
1
FLEXIBLEFIT
REAL
Cross-Correlation
REFINEMENT PROTOCOL--Rigid Body and flexible fitting DETAILS--The domains were initially separately fitted by manual docking and then further optimized using mdff. A model of SmpB C-terminal Tail (KAYEKRREDKKEAVRRALEEL) was added.
2
FLEXIBLEFIT
REAL
Cross-Correlation
REFINEMENT PROTOCOL--Rigid Body and flexible fitting DETAILS--each subdomain (H2b-c, H5, pk1, pk2, pk3, pk4) were initially separately fitted by manual docking and then further optimized using mdff.
原子モデル構築
PDB chain-ID: B / Source name: PDB / タイプ: experimental model