日期：2014-10-24
DOI：http://dx.doi.org/10.1016/j.cell.2014.10.001
真核生物翻译起始期间，其实tRNA不完全插入到40S核糖体亚基上的P译码位点上。这个构象(POUT)是与用于AUG起始密码子的扫描mRNA兼容。与AUG进行碱基配对被认为是促进异构化趋向更稳定的构象(PIN)，即捕捉扫描并促进eIF1从40S亚基分离。在这里，我们提出一个cryoEM重组，是在4.0A离心率下的酵母其实前复合物与eIF1释放之前PIN状态下的起始tRNA。该结构揭示了利用eIF1A的N-末端尾部，密码-反密码双链的的稳定性，包括在eIF1结构里可能的有助于其随后的释放的变化，以及在eIF2构象里的变化。mRNA贯穿整个mRNA间隙和生成到eIF2α、eIF1A的调节区域的连接，以及别环绕AUG密码子的相邻碱基的核糖体元素允许识。
原文标题：Structural Changes Enable Start Codon Recognition by the Eukaryotic Translation Initiation Complex
原文摘要：During eukaryotic translation initiation, initiator tRNA does not insert fully into the P decoding site on the 40S ribosomal subunit. This conformation (POUT) is compatible with scanning mRNA for the AUG start codon. base pairing with AUG is thought to promote isomerization to a more stable conformation (PIN) that arrests scanning and promotes dissociation of eIF1 from the 40S subunit. Here, we present a cryoEM reconstruction of a yeast preinitiation complex at 4.0 Å resolution with initiator tRNA in the PIN state, prior to eIF1 release. The structure reveals stabilization of the codon-anticodon duplex by the N-terminal tail of eIF1A, changes in the structure of eIF1 likely instrumental in its subsequent release, and changes in the conformation of eIF2. The mRNA traverses the entire mRNA cleft and makes connections to the regulatory domain of eIF2α, eIF1A, and ribosomal elements that allow recognition of context nucleotides surrounding the AUG codon.
原文地址：http://www.cell.com/cell/abstract/S0092-8674(14)01281-1
来源： Cell浏览次数：3
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