Communication between eukaryotic translation initiation factors 5 and 1A within the ribosomal pre-initiation complex plays a role in start site selection
Communication between eukaryotic translation initiation factors 5 and 1A within the ribosomal pre-initiation complex plays a role in start site selection
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DOI：
10.1016/j.jmb.2005.11.083
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发表时间：
2006-02-24
影响因子：
5.6
通讯作者：
Lorsch, JR
中科院分区：
文献类型：
--
作者：
Maag, D;Algire, MA;Lorsch, JR
在真核翻译起始过程中，43 S核糖体起始前复合体扫描mRNAs，寻找开始翻译的AUG密码子。开始密码子识别停止扫描，并触发一系列事件，使复合体在mRNA上的那个点开始翻译。以往的体外和体内研究表明，真核细胞启动因子1、2和5在这些事件中发挥关键作用。此外，最近有报道称，eIF1A的C-末端结构域参与了起始密码子识别的保真度维持。这些因素共同作用以确保起点选择的保真度的分子机制仍然知之甚少。在这里，我们报告了在体外重组酵母翻译起始系统中eIF1A、eIF5和AUG密码子之间能量相互作用的定量表征。我们的结果表明，43 S复合体对AUG密码子的识别触发了eIF5和ORA之间的相互作用，导致了预引发复合体两种状态之间的平衡位移。这种依赖于Aug的改变可以是从扫描能力状态到扫描不能力状态的重组。EIF1A和eIF5的突变增加了体内非AUG密码子的起始，削弱了这两个因子在AUG识别时的相互作用，而特别是加强了对UUG密码子的反应。这些数据有力地表明，eIF1A和eIF5之间的相互作用参与了体内维持起始密码子识别的保真度。(C)2005爱思唯尔有限公司。保留所有权利。
During eukaryotic translation initiation, the 43 S ribosomal pre-initiation complex scans the mRNA in search of an AUG codon at which to begin translation. Start codon recognition halts scanning and triggers a number of events that commit the complex to beginning translation at that point on the mRNA. Previous studies in vitro and in vivo have indicated that eukaryotic initiation factors (eIFs) 1, 2 and 5 play key roles in these events. In addition, it was reported recently that the C-terminal domain of eIF1A is involved in maintaining the fidelity of start codon recognition. The molecular mechanisms by which these factors work together to ensure fidelity of start site selection remain poorly understood. Here, we report the quantitative characterization of energetic interactions between eIF1A, eIF5 and the AUG codon in an in vitro reconstituted yeast translation initiation system. Our results show that recognition of an AUG codon by the 43 S complex triggers an interaction between eIF5 and ORA, resulting in a shift in the equilibrium between two states of the pre-initiation complex. This AUG-dependent change may be a reorganization from a scanning-competent state to a scanning-incompetent state. Mutations in both eIF1A and eIF5 that increase initiation at non-AUG codons in vivo weaken the interaction between the two factors upon AUG recognition, while specifically strengthening it in response to a UUG codon. These data suggest strongly that the interaction between eIF1A and eIF5 is involved in maintaining the fidelity of start codon recognition in vivo. (c) 2005 Elsevier Ltd. All rights reserved.