Structures of the E. coli translating ribosome with SRP and its receptor and with the translocon.
Structures of the E. coli translating ribosome with SRP and its receptor and with the translocon.
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DOI：
10.1038/ncomms10471
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发表时间：
2016-01-25
影响因子：
16.6
通讯作者：
Ban N
中科院分区：
文献类型：
--
作者：
Jomaa A;Boehringer D;Leibundgut M;Ban N
靶向膜的共翻译蛋白是一个普遍保守的过程。核心步骤包括通过信号识别颗粒识别货物并将其移交给Sec易位子。在这里，我们提出了关键的共翻译靶向复合物的快照解决了冷冻电子显微镜在近原子分辨率，建立大肠杆菌翻译核糖体，信号识别颗粒和translocon之间的分子接触。我们的研究结果揭示了调节信号序列的闭锁，信号识别颗粒及其受体的异源二聚体结构域的释放，以及信号序列向易位子的移交的构象变化。我们还观察到，信号识别颗粒和转位子插入到核糖体隧道的特定结构元件，以重塑它，可能感生链。我们的工作提供了结构证据的构象状态的信号识别颗粒和其受体引发的转座结合的核糖体新生链复合物。 蛋白质共翻译插入膜需要核糖体结合的信号识别颗粒（SRP）和膜结合的易位子之间的相互作用。在这里，作者使用cryo-EM和单粒子重建来获得共翻译蛋白靶向过程的全面视图。
Co-translational protein targeting to membranes is a universally conserved process. Central steps include cargo recognition by the signal recognition particle and handover to the Sec translocon. Here we present snapshots of key co-translational-targeting complexes solved by cryo-electron microscopy at near-atomic resolution, establishing the molecular contacts between the Escherichia coli translating ribosome, the signal recognition particle and the translocon. Our results reveal the conformational changes that regulate the latching of the signal sequence, the release of the heterodimeric domains of the signal recognition particle and its receptor, and the handover of the signal sequence to the translocon. We also observe that the signal recognition particle and the translocon insert-specific structural elements into the ribosomal tunnel to remodel it, possibly to sense nascent chains. Our work provides structural evidence for a conformational state of the signal recognition particle and its receptor primed for translocon binding to the ribosome–nascent chain complex. The co-translational insertion of proteins into membranes requires interaction between a ribosome-bound signal recognition particle (SRP) and a membrane-bound translocon. Here the authors use cryo-EM and single particle reconstructions to obtain a comprehensive view of the co-translational protein targeting process.