Grzela R, Strokovska L, Andrieu J-P, Dublet B, Zagorski W, Chroboczek J
Institute of Biochemistry and Biophysics (IBB), Polish Academy of Sciences, Warsaw, Poland.
Biochimie. 2006 Jul;88(7):887-96. doi: 10.1016/j.biochi.2006.02.012. Epub 2006 Mar 31.
Potyvirus RNA contains at the 5' end a covalently linked virus-encoded protein VPg, which is required for virus infectivity. This role has been attributed to VPg interaction with the eukaryotic translation initiation factor eIF4E, a cap-binding protein. We characterized the dissociation constants for the interaction of the potato virus Y VPg with different plant eIF4Es and its isoforms and mapped the eIF(iso)4E attachment region on VPg. VPg/eIF4E interaction results in the inhibition of cell-free protein synthesis, and we show that it stems from the liberation of the cap moiety from the complex with eIF4E. Since VPg does not attach the cap, it appears that VPg induces changes in the eIF4E structure, diminishing its affinity to the cap. We show here that the initiation complex scaffold protein eIF(iso)4G increases VPg interaction with eIF(iso)4E. These data together suggest similar cap and VPg interactions with eIF4E and characterize VPg as a novel eIF4E-binding protein, which inhibits host protein synthesis at a very early stage of the initiation complex formation through the inhibition of cap attachment to the initiation factor eIF4E.
马铃薯Y病毒属病毒RNA在5'端含有一个与病毒编码蛋白VPg共价连接的结构，该结构是病毒感染性所必需的。这一作用归因于VPg与真核翻译起始因子eIF4E（一种帽结合蛋白）的相互作用。我们表征了马铃薯Y病毒VPg与不同植物eIF4E及其异构体相互作用的解离常数，并绘制了VPg上的eIF(iso)4E附着区域。VPg/eIF4E相互作用导致无细胞蛋白质合成受到抑制，我们表明这源于帽部分从与eIF4E的复合物中释放出来。由于VPg不附着帽，似乎VPg诱导了eIF4E结构的变化，降低了其对帽的亲和力。我们在此表明起始复合物支架蛋白eIF(iso)4G增加了VPg与eIF(iso)4E的相互作用。这些数据共同表明帽和VPg与eIF4E的相互作用相似，并将VPg表征为一种新型的eIF4E结合蛋白，它通过抑制帽与起始因子eIF4E的附着，在起始复合物形成的非常早期阶段抑制宿主蛋白质合成。
