Structural and molecular basis for Cardiovirus 2A protein as a viral gene expression switch.
Structural and molecular basis for Cardiovirus 2A protein as a viral gene expression switch.
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DOI：
10.1038/s41467-021-27400-7
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发表时间：
2021-12-09
影响因子：
16.6
通讯作者：
Brierley I
中科院分区：
文献类型：
--
作者：
Hill CH;Pekarek L;Napthine S;Kibe A;Firth AE;Graham SC;Caliskan N;Brierley I
心脏病毒中的程序性-1核糖体移码（PRF）由2A蛋白激活，2A蛋白是一种多功能毒力因子，也抑制帽依赖性翻译起始。在这里，我们提出的X-射线晶体结构的2A和显示，它选择性地结合到一个假结样构象的PRF刺激RNA元件在病毒基因组中。使用光镊，我们证明，2A稳定这个RNA元件，可能解释了在2A的存在下，PRF效率的增加。接下来，我们证明了2A和小核糖体亚基之间的强相互作用，并提出了一个cryo-EM结构的2A绑定到启动70 S核糖体。2A的多个拷贝与16 S rRNA结合，在那里它们可以与起始和延伸因子竞争结合。总之，这些结果定义了2A识别RNA的结构基础，显示了2A介导的RNA假结稳定如何促进PRF，并揭示了2A积累如何在病毒感染期间关闭翻译。许多RNA病毒利用程序性-1核糖体移码（PRF）来扩展其编码能力并优化病毒蛋白的产生。在这里，作者报告了来自心脏病毒的蛋白2A的结构和生物物理分析，并深入了解其PRF刺激功能的机制。
Programmed –1 ribosomal frameshifting (PRF) in cardioviruses is activated by the 2A protein, a multi-functional virulence factor that also inhibits cap-dependent translational initiation. Here we present the X-ray crystal structure of 2A and show that it selectively binds to a pseudoknot-like conformation of the PRF stimulatory RNA element in the viral genome. Using optical tweezers, we demonstrate that 2A stabilises this RNA element, likely explaining the increase in PRF efficiency in the presence of 2A. Next, we demonstrate a strong interaction between 2A and the small ribosomal subunit and present a cryo-EM structure of 2A bound to initiated 70S ribosomes. Multiple copies of 2A bind to the 16S rRNA where they may compete for binding with initiation and elongation factors. Together, these results define the structural basis for RNA recognition by 2A, show how 2A-mediated stabilisation of an RNA pseudoknot promotes PRF, and reveal how 2A accumulation may shut down translation during virus infection. Many RNA viruses employ programmed –1 ribosomal frameshifting (PRF) to expand their coding capacity and optimize production of viral proteins. Here, the authors report structural and biophysical analysis of protein 2A from a cardiovirus, with insights into the mechanism of its PRF-stimulatory function.