Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Shandong Province Key Laboratory of Agricultural Microbiology, Tai'an 271018, P.R. China.
Nucleic Acids Res. 2020 Jan 10;48(1):390-404. doi: 10.1093/nar/gkz1073.
Internal ribosome entry sites (IRESes) were first reported in RNA viruses and subsequently identified in cellular mRNAs. In this study, IRES activity of the 5'-UTR in Wheat yellow mosaic virus (WYMV) RNA1 was identified, and the 3'-UTR synergistically enhanced this IRES activity via long-distance RNA-RNA interaction between C80U81and A7574G7575. Within the 5'-UTR, the hairpin 1(H1), flexible hairpin 2 (H2) and linker region (LR1) between H1 and H2 played an essential role in cap-independent translation, which is associated with the structural stability of H1, length of discontinuous stems and nucleotide specificity of the H2 upper loop and the long-distance RNA-RNA interaction sites in LR1. The H2 upper loop is a target region of the eIF4E. Cytosines (C55, C66, C105 and C108) in H1 and H2 and guanines (G73, G79 and G85) in LR1 form discontinuous and alternative base pairing to maintain the dynamic equilibrium state, which is used to elaborately regulate translation at a suitable level. The WYMV RNA1 5'-UTR contains a novel IRES, which is different from reported IRESes because of the dynamic equilibrium state. It is also suggested that robustness not at the maximum level of translation is the selection target during evolution of WYMV RNA1.
内部核糖体进入位点（IRESes）最初在 RNA 病毒中被报道，随后在细胞 mRNA 中被鉴定。在本研究中，鉴定了小麦黄花叶病毒（WYMV）RNA1 5'UTR 中的 IRES 活性，并且 3'UTR 通过 C80U81 和 A7574G7575 之间的长距离 RNA-RNA 相互作用协同增强了这种 IRES 活性。在 5'UTR 中，发夹 1（H1）、柔性发夹 2（H2）和 H1 与 H2 之间的连接区（LR1）在无帽依赖性翻译中发挥重要作用，这与 H1 的结构稳定性、不连续茎的长度以及 H2 上环的核苷酸特异性和 LR1 中的长距离 RNA-RNA 相互作用位点有关。H2 上环是 eIF4E 的靶标区域。H1 和 H2 中的胞嘧啶（C55、C66、C105 和 C108）和 LR1 中的鸟嘌呤（G73、G79 和 G85）形成不连续的替代碱基配对，以维持动态平衡状态，这用于精细调节适当水平的翻译。WYMV RNA1 5'UTR 包含一个新的 IRES，由于动态平衡状态，它与报道的 IRESes 不同。还表明，在 WYMV RNA1 的进化过程中，稳健性不是翻译的最高水平，而是选择的目标。
