Burgui Idoia, Aragón Tomás, Ortín Juan, Nieto Amelia
Centro Nacional de Biotecnología (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain.
J Gen Virol. 2003 Dec;84(Pt 12):3263-3274. doi: 10.1099/vir.0.19487-0.
It has previously been shown that influenza virus NS1 protein enhances the translation of viral but not cellular mRNAs. This enhancement occurs by increasing the rate of translation initiation and requires the 5'UTR sequence, common to all viral mRNAs. In agreement with these findings, we show here that viral mRNAs, but not cellular mRNAs, are associated with NS1 during virus infection. We have previously reported that NS1 interacts with the translation initiation factor eIF4GI, next to its poly(A)-binding protein 1 (PABP1)-interacting domain and that NS1 and eIF4GI are associated in influenza virus-infected cells. Here we show that NS1, although capable of binding poly(A), does not compete with PABP1 for association with eIF4GI and, furthermore, that NS1 and PABP1 interact both in vivo and in vitro in an RNA-independent manner. The interaction maps between residues 365 and 535 in PABP1 and between residues 1 and 81 in NS1. These mapping studies, together with those previously reported for NS1-eIF4GI and PABP1-eIF4GI interactions, imply that the binding of all three proteins would be compatible. Collectively, these and previously published data suggest that NS1 interactions with eIF4GI and PABP1, as well as with viral mRNAs, could promote the specific recruitment of 43S complexes to the viral mRNAs.
先前的研究表明，流感病毒NS1蛋白可增强病毒mRNA而非细胞mRNA的翻译。这种增强是通过提高翻译起始速率实现的，并且需要所有病毒mRNA共有的5'UTR序列。与这些发现一致，我们在此表明，在病毒感染期间，病毒mRNA而非细胞mRNA与NS1相关联。我们先前曾报道，NS1在其与多聚腺苷酸结合蛋白1（PABP1）相互作用结构域旁边与翻译起始因子eIF4GI相互作用，并且NS1和eIF4GI在流感病毒感染的细胞中相关联。在此我们表明，NS1虽然能够结合多聚腺苷酸，但并不与PABP1竞争与eIF4GI的结合，此外，NS1和PABP1在体内和体外均以不依赖RNA的方式相互作用。绘制了PABP1中365至535位残基与NS1中1至81位残基之间的相互作用图谱。这些图谱研究，连同先前报道的NS1-eIF4GI和PABP1-eIF4GI相互作用的研究，表明这三种蛋白质的结合是兼容的。总体而言，这些以及先前发表的数据表明，NS1与eIF4GI和PABP1的相互作用，以及与病毒mRNA的相互作用，可能会促进43S复合物特异性募集到病毒mRNA上。
