A multifactor complex of eIFI, cIF2, eIF3, eIF5, and tRNAiMet promotes initiation complex assembly and couples GTP hydrolysis to AUG recognition
A multifactor complex of eIFI, cIF2, eIF3, eIF5, and tRNAiMet promotes initiation complex assembly and couples GTP hydrolysis to AUG recognition
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DOI：
10.1101/sqb.2001.66.403
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发表时间：
2001-01-01
期刊：
影响因子：
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通讯作者：
Hinnebusch, AG
中科院分区：
文献类型：
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作者：
Asano, K;Phan, L;Hinnebusch, AG
我们实验室最近的工作揭示了 eIF 之间的物理相互作用网络，在 48S 复合物组装过程中，eIF 参与 Met-tRNAi Met 和 mRNA 与 40S 亚基的结合。出乎意料的是，eIF5 的羧基末端结构域 (CTD)（TC 的 GAP）在这些相互作用中发挥着核心作用，桥接了 eIF3 与 TC、eIF1 和 eIF4G 的关联。我们已经鉴定出包含 eIF 1、2、3、5 和 Met-tRNAi Met 的多因子复合物 (MFC)，其可以独立于 40S 核糖体存在，这表明 MFC 的成分作为预制单元与 40S 核糖体结合。体外实验结果表明，MFC 的形成促进 TC 和 mRNA 与 40S 核糖体的结合。体内分析表明，在扫描过程中，eIF5 依赖性 GTP 水解与起始密码子识别的有效耦合需要通过 MFC 将 eIF 1 和 5 稳定掺入 48S 复合物中。
Recent work from our laboratory has revealed a network of physical interactions among eIFs that participate in the binding of Met-tRNAi Met and mRNA to 40S subunits during assembly of the 48S complex. Unexpectedly, the carboxy-terminal domain (CTD) of eIF5, a GAP for the TC, plays a central role in these interactions, bridging association of eIF3 with the TC, eIF1, and eIF4G. We have identified a multifactor complex (MFC) containing eIFs 1, 2, 3, 5, and Met-tRNAi Met that can exist free of 40S ribosomes, suggesting that constituents of the MFC bind to the 40S ribosome as a preformed unit. Results from in vitro experiments indicate that formation of the MFC promotes binding of TC and mRNA to the 40S ribosome. In vivo analysis indicates that stable incorporation of eIFs 1 and 5 into the 48S complex, via the MFC, is required for efficient coupling of eIF5-dependent GTP hydrolysis with start codon recognition during the scanning process.