Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Shandong Province Key Laboratory of Agricultural Microbiology, Tai'an 271018, PR China.
Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Shandong Province Key Laboratory of Agricultural Microbiology, Tai'an 271018, PR China.
Int J Biol Macromol. 2024 Jan;254(Pt 3):128062. doi: 10.1016/j.ijbiomac.2023.128062. Epub 2023 Nov 13.
Some viral proteins are translated cap-independently via the internal ribosome entry site (IRES), which maintains conservative characteristic among different isolates of the same virus species. However, IRES activity showed a 7-fold variance in RNA2 of wheat yellow mosaic virus (WYMV) HC and LYJN isolates in this study. Based on RNA structure probing and mutagenesis assay, the loosened middle stem of H1 and the hepta-nucleotide top loop of H2 in the LYJN isolate synergistically ensured higher IRES activity than that in the HC isolate. In addition, the conserved top loop of H1 ensured basic IRES activity in HC and LYJN isolates. WYMV RNA2 5'-UTR specifically interacted with the wheat eIF4E, accomplished by the top loop of H1 in the HC isolate or the top loop of H1 and H2 in the LYJN isolate. The high IRES activity of the WYMV RNA2 LYJN isolate was regulated by two eIF4E-binding sites, which showed a synergistic effect mediated by the proximity of the H1 and H2 top loops owing to the flexibility of the middle stem in H1. This report presents a novel evolution pattern of IRES, which altered the number of eIF4E-binding sites to regulate IRES activity.
一些病毒蛋白通过内部核糖体进入位点（IRES）进行无帽依赖性翻译，该位点在同一病毒种的不同分离株之间保持保守特征。然而，在本研究中，小麦黄花叶病毒（WYMV）HC 和 LYJN 分离株的 RNA2 的 IRES 活性表现出 7 倍的差异。基于 RNA 结构探测和突变分析，LYJN 分离株中 H1 的中间茎松弛和 H2 的七核苷酸顶部环协同作用，确保了比 HC 分离株更高的 IRES 活性。此外，H1 的保守顶部环确保了 HC 和 LYJN 分离株中基本的 IRES 活性。WYMV RNA2 5'-UTR 特异性地与小麦 eIF4E 相互作用，这是由 HC 分离株中的 H1 顶部环或 LYJN 分离株中的 H1 和 H2 顶部环完成的。WYMV RNA2 LYJN 分离株的高 IRES 活性受到两个 eIF4E 结合位点的调节，由于 H1 中的中间茎的灵活性，这两个结合位点通过 H1 和 H2 顶部环的接近性表现出协同作用。本报告提出了一种新的 IRES 进化模式，通过改变 eIF4E 结合位点的数量来调节 IRES 活性。
