Activity of the hepatitis A virus IRES requires association between the cap-binding translation initiation factor (eIF4E) and eIF4G
Activity of the hepatitis A virus IRES requires association between the cap-binding translation initiation factor (eIF4E) and eIF4G
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DOI：
10.1128/jvi.75.17.7854-7863.2001
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发表时间：
2001-09-01
影响因子：
5.4
通讯作者：
Jackson, RJ
中科院分区：
文献类型：
--
作者：
Ali, IK;McKendrick, L;Jackson, RJ
翻译起始因子eIF 4 E和完整的eIF 4G多肽是否是依赖于甲型肝炎病毒（HAV）的IRES（内部核糖体进入位点）的起始所必需的问题，已经使用标准和eIF 4G耗尽的兔网织红细胞裂解物中的体外翻译进行了检查。与先前的出版物一致，HAV IRES在所有小核糖核酸病毒IRES中是独特的，因为如果翻译起始因子eIF 4G被口蹄疫L-蛋白酶切割，则其被抑制。此外，HAV IRES通过加入eIF 4 E结合蛋白1而被抑制，该蛋白1与eIF 4 E紧密结合并将其隔离，从而防止其与eIF 4G结合。加入m（7）GpppG cap类似物也能抑制HAV IRES，无论所测试的RNA是否被加帽。因此，在HAV IRES上的起始需要eIF 4 E与eIF 4G结合，并且eIF 4 E的帽结合口袋是空的且未被占据。这表明了两种替代模型：（i）起始需要IRES中的内部位点与eIF 4 E/4G之间的直接相互作用，除了任何直接的eIF 4G-RNA相互作用之外，这种相互作用还涉及eIF 4 E的帽结合口袋;或（ii）它需要处于特定构象的eIF 4G，只有当eIF 4 E与其结合时，eIF 4 E的帽结合口袋未被占据时，才能获得这种构象。
The question of whether translation initiation factor eIF4E and the complete eIF4G polypeptide are required for initiation dependent on the IRES (internal ribosome entry site) of hepatitis A virus (HAV) has been examined using in vitro translation in standard and eIF4G-depleted rabbit reticulocyte lysates. In agreement with previous publications, the HAV IRES is unique among all picornavirus IRESs in that it was inhibited if translation initiation factor eIF4G was cleaved by foot-and-mouth disease L-proteases. In addition, the HAV IRES was inhibited by addition of eIF4E-binding protein 1, which binds tightly to eIF4E and sequesters it, thus preventing its association with eIF4G. The HAV IRES was also inhibited by addition of m(7)GpppG cap analogue, irrespective of whether the RNA tested was capped or not. Thus, initiation on the HAV IRES requires that eIF4E be associated with eIF4G and that the cap-binding pocket of eIF4E be empty and unoccupied. This suggests two alternative models: (i) initiation requires a direct interaction between an internal site in the IRES and eIF4E/4G, an interaction which involves the cap-binding pocket of eIF4E in addition to any direct eIF4G-RNA interactions; or (ii) it requires eIF4G in a particular conformation which can be attained only if eIF4E is bound to it, with the cap-binding pocket of the eIF4E unoccupied.