RQT complex dissociates ribosomes collided on endogenous RQC substrate SDD1
RQT complex dissociates ribosomes collided on endogenous RQC substrate SDD1
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DOI：
10.1038/s41594-020-0393-9
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发表时间：
2020-03-23
影响因子：
16.8
通讯作者：
Inada, Toshifumi
中科院分区：
文献类型：
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作者：
Matsuo, Yoshitaka;Tesina, Petr;Inada, Toshifumi
从酿酒酵母中鉴定SDD1 mRNA作为内源性RQC底物，可以分析翻译停滞和碰撞核糖体的Hel2依赖性聚泛素化的机制，以提供对核糖体解离的洞察。碰撞的核糖体被识别用于随后的解离，随后是新生肽的降解。然而，内源性RQC诱导序列和泛素依赖性核糖体解离的机制仍然知之甚少。在这里，我们确定SDD1信使RNA从酿酒酵母作为内源性RQC底物，并揭示其mRNA依赖性和新生肽依赖性的翻译停滞的机制。SDD1 mRNA的体外翻译使Hel2依赖的多聚泛素化的碰撞二体，优先，三体的重建。不同的三体架构，可视化使用冷冻EM，提供了更有效的识别Hel2相比，二体的结构基础。随后，RQC触发因子（RQT）复合物的Slh 1解旋酶亚基优先以ATP依赖性方式解离第一个停滞的多聚遍在蛋白化核糖体。总之，这些研究结果提供了基本的机制RQC及其在维持细胞蛋白质稳态的生理作用的见解。
Identification of SDD1 mRNA from Saccharomyces cerevisiae as an endogenous RQC substrate allows analysis of the mechanism underlying translational stalling and Hel2-dependent polyubiquitination of collided ribosomes to provide insight into ribosome dissociation.Ribosome-associated quality control (RQC) represents a rescue pathway in eukaryotic cells that is triggered upon translational stalling. Collided ribosomes are recognized for subsequent dissociation followed by degradation of nascent peptides. However, endogenous RQC-inducing sequences and the mechanism underlying the ubiquitin-dependent ribosome dissociation remain poorly understood. Here, we identified SDD1 messenger RNA from Saccharomyces cerevisiae as an endogenous RQC substrate and reveal the mechanism of its mRNA-dependent and nascent peptide-dependent translational stalling. In vitro translation of SDD1 mRNA enabled the reconstitution of Hel2-dependent polyubiquitination of collided disomes and, preferentially, trisomes. The distinct trisome architecture, visualized using cryo-EM, provides the structural basis for the more-efficient recognition by Hel2 compared with that of disomes. Subsequently, the Slh1 helicase subunit of the RQC trigger (RQT) complex preferentially dissociates the first stalled polyubiquitinated ribosome in an ATP-dependent manner. Together, these findings provide fundamental mechanistic insights into RQC and its physiological role in maintaining cellular protein homeostasis.