α-Helical nascent polypeptide chains visualized within distinct regions of the ribosomal exit tunnel
α-Helical nascent polypeptide chains visualized within distinct regions of the ribosomal exit tunnel
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DOI：
10.1038/nsmb.1756
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发表时间：
2010-03-01
影响因子：
16.8
通讯作者：
Beckmann, Roland
中科院分区：
文献类型：
--
作者：
Bhushan, Shashi;Gartmann, Marco;Beckmann, Roland
随着翻译的进行，新生的多肽链穿过核糖体大亚基中的隧道。虽然这种核糖体出口通道曾经被认为只是生长新生链的被动管道，但越来越多的证据表明，它实际上可能在调节翻译和初始蛋白质折叠事件中发挥更积极的作用。在这里，我们已经确定了单粒子冷冻电子显微镜重建的真核80 S核糖体含有新生链与高α-螺旋倾向位于出口隧道内。该地图能够直接可视化的密度螺旋，以及允许网站的相互作用与隧道壁组件被阐明。在隧道的特定区域，新生链采用不同的构象，并建立与隧道组件，核糖体RNA和蛋白质，先前已经牵连在新生链-核糖体相互作用的特定接触。
As translation proceeds, the nascent polypeptide chain passes through a tunnel in the large ribosomal subunit. Although this ribosomal exit tunnel was once thought only to be a passive conduit for the growing nascent chain, accumulating evidence suggests that it may in fact play a more active role in regulating translation and initial protein folding events. Here we have determined single-particle cryo-electron microscopy reconstructions of eukaryotic 80S ribosomes containing nascent chains with high alpha-helical propensity located within the exit tunnel. The maps enable direct visualization of density for helices as well as allowing the sites of interaction with the tunnel wall components to be elucidated. In particular regions of the tunnel, the nascent chain adopts distinct conformations and establishes specific contacts with tunnel components, both ribosomal RNA and proteins, that have been previously implicated in nascent chain-ribosome interaction.