The C-Terminal Domain of Eukaryotic Initiation Factor 5 Promotes Start Codon Recognition by Its Dynamic Interplay with eIF1 and eIF2β
The C-Terminal Domain of Eukaryotic Initiation Factor 5 Promotes Start Codon Recognition by Its Dynamic Interplay with eIF1 and eIF2β
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DOI：
10.1016/j.celrep.2012.04.007
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发表时间：
2012-06-01
期刊：
影响因子：
8.8
通讯作者：
Wagner, Gerhard
中科院分区：
文献类型：
--
作者：
Luna, Rafael E.;Arthanari, Haribabu;Wagner, Gerhard
识别 mRNA 上正确的起始密码子对于蛋白质合成至关重要，蛋白质合成需要扫描并涉及真核起始因子 (eIF) eIF1、eIF1A、eIF2 和 eIF5。 eIF5 的羧基末端结构域 (CTD) 刺激 43S 起始复合物 (PIC) 组装；然而，其在扫描和起始密码子选择中的确切作用仍然未知。使用核磁共振（NMR）光谱，我们鉴定了 eIF1 和 eIF2 beta 在 eIF5-CTD 上的结合位点，并发现它们部分重叠。共同界面中选定的 eIF5 残基发生突变会特异性破坏与这两个因子的相互作用。遗传和生化证据表明，这些 eIF5-CTD 突变会破坏起始密码子识别，并通过废除 eIF5-CTD 与 eIF2 beta 的结合来阻碍 eIF1 从 PIC 中释放。这项研究提供了关于 eIF5-CTD 与 eIF1 和 eIF2 beta 的动态相互作用在起始密码子处将 PIC 从开放状态切换到封闭状态中的作用的机制见解。
Recognition of the proper start codon on mRNAs is essential for protein synthesis, which requires scanning and involves eukaryotic initiation factors (eIFs) eIF1, eIF1A, eIF2, and eIF5. The carboxyl terminal domain (CTD) of eIF5 stimulates 43S preinitiation complex (PIC) assembly; however, its precise role in scanning and start codon selection has remained unknown. Using nuclear magnetic resonance (NMR) spectroscopy, we identified the binding sites of eIF1 and eIF2 beta on eIF5-CTD and found that they partially overlapped. Mutating select eIF5 residues in the common interface specifically disrupts interaction with both factors. Genetic and biochemical evidence indicates that these eIF5-CTD mutations impair start codon recognition and impede eIF1 release from the PIC by abrogating eIF5-CTD binding to eIF2 beta. This study provides mechanistic insight into the role of eIF5-CTD's dynamic interplay with eIF1 and eIF2 beta in switching PICs from an open to a closed state at start codons.