Binding of a viral IRES to the 40S subunit occurs in two successive steps mediated by eS25.
Binding of a viral IRES to the 40S subunit occurs in two successive steps mediated by eS25.
复制标题
病毒 IRES 与 40S 亚基的结合发生在 eS25 介导的两个连续步骤中。
DOI：
10.1093/nar/gkaa547
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发表时间：
2020
影响因子：
14.9
通讯作者：
Thompson,SunnieR
中科院分区：
文献类型：
--
作者：
Walters,Beth;Axhemi,Armend;Jankowsky,Eckhard;Thompson,SunnieR
内部核糖体进入位点（IRES）如何募集核糖体以启动mRNA翻译的机制尚未完全了解。我们研究了40 S亚基是如何被蟋蟀麻痹病毒基因间区（CrPV IGR）IRES募集形成稳定的40 S-IRES复合物的。动力学结合研究表明，CrPV IGR和40 S亚基之间的复合物的形成包括两个步骤：一个初始的快速结合步骤的IRES的40 S核糖体亚基，随后由一个缓慢的单分子反应与构象变化，稳定的复合物一致。我们进一步表明，核糖体蛋白S25（eS 25），这是所需的功能和结构多样的IRES，影响复合物形成的两个步骤。降低CrPV IGR IRES活性的eS 25突变要么降低40 S-IRES复合物的形成，要么增加形成稳定40 S-IRES复合物所需的构象变化速率。我们的数据与模型一致，其中eS 25促进CrPV IGR IRES与40 S的初始结合，同时确保稳定40 S-IRES复合物的构象变化不会过早发生。
The mechanism for how internal ribosome entry sites (IRESs) recruit ribosomes to initiate translation of an mRNA is not completely understood. We investigated how a 40S subunit was recruited by the cricket paralysis virus intergenic region (CrPV IGR) IRES to form a stable 40S–IRES complex. Kinetic binding studies revealed that formation of the complex between the CrPV IGR and the 40S subunit consisted of two-steps: an initial fast binding step of the IRES to the 40S ribosomal subunit, followed by a slow unimolecular reaction consistent with a conformational change that stabilized the complex. We further showed that the ribosomal protein S25 (eS25), which is required by functionally and structurally diverse IRESs, impacts both steps of the complex formation. Mutations in eS25 that reduced CrPV IGR IRES activity either decreased 40S–IRES complex formation, or increased the rate of the conformational change that was required to form a stable 40S–IRES complex. Our data are consistent with a model in which eS25 facilitates initial binding of the CrPV IGR IRES to the 40S while ensuring that the conformational change stabilizing the 40S–IRES complex does not occur prematurely.