Mimicry of Canonical Translation Elongation Underlies Alanine Tail Synthesis in RQC.
Mimicry of Canonical Translation Elongation Underlies Alanine Tail Synthesis in RQC.
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DOI：
10.1016/j.molcel.2020.11.001
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发表时间：
2021-01-07
期刊：
影响因子：
16
通讯作者：
Pfeffer S
中科院分区：
文献类型：
--
作者：
Filbeck S;Cerullo F;Paternoga H;Tsaprailis G;Joazeiro CAP;Pfeffer S
终止的翻译产生大的核糖体亚基，其被tRNA连接的起始链阻碍，所述起始链是核糖体相关质量控制（RQC）的底物。细菌RqcH，一种广泛保守的RQC因子，感知到阻塞并招募tRNAAla（UGC）用聚丙氨酸降解决定子修饰新生链C-末端。然而，如何RqcH和真核同源物，尽管他们的相对简单的架构，合成这样的C-末端尾巴在一个小的核糖体亚基和mRNA的情况下仍然未知。在这里，我们提出了枯草芽孢杆菌RQC复合物的冷冻EM结构，代表不同的丙氨酸尾合成步骤。这些结构解释了tRNAla在募集到A位点期间如何通过反密码子阅读进行选择，并揭示了RqcH中引人注目的铰链样运动，导致tRNAla进入与肽基转移相关的杂合A/P状态。最后，我们提供了结构，生物化学和分子遗传学的证据，确定热休克蛋白15同源物作为一种新的RQC组件，通过稳定的P-位点tRNA构象完成循环。因此，丙氨酸加尾遵循与经典翻译延伸惊人相似的机械原理。通过核糖体相关质量控制（RQC）标记不完全形成的初生链用于蛋白水解。在细菌RQC中，这由C-末端丙氨酸加尾介导。Filbeck等人使用cryo-EM阐明了丙氨酸加尾的结构基础，发现Hsp 15/RqcP是一个重要因素，并揭示了C末端加尾遵循与经典翻译延伸相似的原理。
Aborted translation produces large ribosomal subunits obstructed with tRNA-linked nascent-chains, which are substrates of Ribosome-associated Quality Control (RQC). Bacterial RqcH, a widely-conserved RQC factor, senses the obstruction and recruits tRNAAla(UGC) to modify nascent-chain C-termini with a polyalanine-degron. However, how RqcH and eukaryotic homologs, despite their relatively simple architecture, synthesize such C-terminal tails in the absence of a small ribosomal subunit and mRNA has remained unknown. Here we present cryo-EM structures of Bacillus subtilis RQC complexes representing different Ala-tail synthesis steps. The structures explain how tRNAAla is selected via anticodon reading during recruitment to the A-site, and uncover striking hinge-like movements in RqcH leading tRNAAla into a hybrid A/P-state associated with peptidyl-transfer. Finally, we provide structural, biochemical and molecular genetic evidence identifying the Hsp15 homolog as a novel RQC component that completes the cycle by stabilizing the P-site tRNA conformation. Ala-tailing thus follows mechanistic principles surprisingly similar to canonical translation elongation. Incompletely-made nascent-chains are tagged for proteolysis by Ribosome-associated Quality Control (RQC). In bacterial RQC, this is mediated by C-terminal alanine-tailing. Filbeck et al. elucidate the structural basis for alanine-tailing using cryo-EM, discover Hsp15/RqcP as an essential factor, and reveal that C-terminal tailing follows similar principles to canonical translation elongation.
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影响因子：
3.3
作者：
Defenouillère Q;Namane A;Mouaikel J;Jacquier A;Fromont-Racine M
通讯作者：
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DOI：
10.1073/pnas.0812819106
发表时间：
2009-02-17
影响因子：
11.1
作者：
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DOI：
10.1073/pnas.68.12.3163
发表时间：
1971-01-01
影响因子：
11.1
作者：
CASKEY, CT;BEAUDET, AL;ROSMAN, M
通讯作者：
ROSMAN, M
影响因子：
16
作者：
Kuroha, Kazushige;Zinoviev, Alexandra;Pestova, Tatyana V.
通讯作者：
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