Butcher Samuel E, Jan Eric
a Department of Biochemistry , University of Wisconsin-Madison , Madison , WI , USA.
b Department of Biochemistry and Molecular Biology , University of British Columbia , Vancouver , BC , Canada.
RNA Biol. 2016 Nov;13(11):1068-1074. doi: 10.1080/15476286.2016.1219833. Epub 2016 Aug 11.
Viruses maintain compact genomes that must be packaged within capsids typically less than 200 nanometers in diameter. Therefore, instead of coding for a full set of genes needed for replication, viruses have evolved remarkable strategies for co-opting the host cellular machinery. Additionally, viruses often increase the coding capacity of their own genomes by employing overlapping open reading frames (ORFs). Some overlapping viral ORFs involve recoding events that are programmed by the viral RNA. During these programmed recoding events, the ribosome is directed to translate in an alternative reading frame. Here we describe how the Dicistroviridae family of viruses utilize an internal ribosome entry site (IRES) in order to recruit ribosomes to initiate translation at a non-AUG codon. The IRES accomplishes this in part by mimicking the structure of a tRNA. Recently, we showed that the Israeli Acute Paralysis Virus (IAPV) member of the Dicistroviridae family utilizes its IRES to initiate translation in 2 different reading frames. Thus, IAPV has evolved an apparently novel recoding mechanism that reveals important insights into translation. Finally, we compare the IAPV structure to other systems that utilize tRNA mimicry in translation.
病毒维持着紧凑的基因组，这些基因组必须包装在直径通常小于200纳米的衣壳内。因此，病毒不是编码复制所需的全套基因，而是进化出了非凡的策略来利用宿主细胞机制。此外，病毒常常通过采用重叠开放阅读框（ORF）来增加自身基因组的编码能力。一些重叠的病毒ORF涉及由病毒RNA编程的重编码事件。在这些编程的重编码事件中，核糖体被引导在另一个阅读框中进行翻译。在这里，我们描述了双顺反子病毒科的病毒如何利用内部核糖体进入位点（IRES）来招募核糖体，以便在非AUG密码子处起始翻译。IRES部分地通过模仿tRNA的结构来实现这一点。最近，我们表明双顺反子病毒科的以色列急性麻痹病毒（IAPV）利用其IRES在2个不同的阅读框中起始翻译。因此，IAPV进化出了一种明显新颖的重编码机制，该机制揭示了有关翻译的重要见解。最后，我们将IAPV的结构与其他在翻译中利用tRNA模拟的系统进行比较。
