Xia Hongjie, Wang Peipei, Wang Guang-Chuan, Yang Jie, Sun Xianlin, Wu Wenzhe, Qiu Yang, Shu Ting, Zhao Xiaolu, Yin Lei, Qin Cheng-Feng, Hu Yuanyang, Zhou Xi
State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China.
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
PLoS Pathog. 2015 Jul 28;11(7):e1005067. doi: 10.1371/journal.ppat.1005067. eCollection 2015 Jul.
RNA helicases and chaperones are the two major classes of RNA remodeling proteins, which function to remodel RNA structures and/or RNA-protein interactions, and are required for all aspects of RNA metabolism. Although some virus-encoded RNA helicases/chaperones have been predicted or identified, their RNA remodeling activities in vitro and functions in the viral life cycle remain largely elusive. Enteroviruses are a large group of positive-stranded RNA viruses in the Picornaviridae family, which includes numerous important human pathogens. Herein, we report that the nonstructural protein 2CATPase of enterovirus 71 (EV71), which is the major causative pathogen of hand-foot-and-mouth disease and has been regarded as the most important neurotropic enterovirus after poliovirus eradication, functions not only as an RNA helicase that 3'-to-5' unwinds RNA helices in an adenosine triphosphate (ATP)-dependent manner, but also as an RNA chaperone that destabilizes helices bidirectionally and facilitates strand annealing and complex RNA structure formation independently of ATP. We also determined that the helicase activity is based on the EV71 2CATPase middle domain, whereas the C-terminus is indispensable for its RNA chaperoning activity. By promoting RNA template recycling, 2CATPase facilitated EV71 RNA synthesis in vitro; when 2CATPase helicase activity was impaired, EV71 RNA replication and virion production were mostly abolished in cells, indicating that 2CATPase-mediated RNA remodeling plays a critical role in the enteroviral life cycle. Furthermore, the RNA helicase and chaperoning activities of 2CATPase are also conserved in coxsackie A virus 16 (CAV16), another important enterovirus. Altogether, our findings are the first to demonstrate the RNA helicase and chaperoning activities associated with enterovirus 2CATPase, and our study provides both in vitro and cellular evidence for their potential roles during viral RNA replication. These findings increase our understanding of enteroviruses and the two types of RNA remodeling activities.
RNA解旋酶和伴侣蛋白是两类主要的RNA重塑蛋白，它们的功能是重塑RNA结构和/或RNA-蛋白质相互作用，是RNA代谢各个方面所必需的。尽管已经预测或鉴定出一些病毒编码的RNA解旋酶/伴侣蛋白，但它们在体外的RNA重塑活性以及在病毒生命周期中的功能仍 largely 难以捉摸。肠道病毒是微小核糖核酸病毒科中的一大类正链RNA病毒，其中包括许多重要的人类病原体。在此，我们报告肠道病毒71型（EV71）的非结构蛋白2CATPase，它是手足口病的主要致病病原体，在脊髓灰质炎病毒根除后被视为最重要的嗜神经性肠道病毒，不仅作为一种RNA解旋酶以三磷酸腺苷（ATP）依赖的方式从3'到5'解开RNA螺旋，而且作为一种RNA伴侣蛋白以双向方式使螺旋不稳定，并独立于ATP促进链退火和复杂RNA结构形成。我们还确定解旋酶活性基于EV71 2CATPase中间结构域，而C末端对于其RNA伴侣活性是不可或缺的。通过促进RNA模板循环利用，2CATPase在体外促进了EV71 RNA合成；当2CATPase解旋酶活性受损时，EV71 RNA复制和病毒粒子产生在细胞中大多被消除，表明2CATPase介导的RNA重塑在肠道病毒生命周期中起关键作用。此外，2CATPase的RNA解旋酶和伴侣活性在另一种重要的肠道病毒柯萨奇A病毒16型（CAV16）中也保守。总之，我们的发现首次证明了与肠道病毒2CATPase相关的RNA解旋酶和伴侣活性，并且我们的研究为它们在病毒RNA复制过程中的潜在作用提供了体外和细胞证据。这些发现增加了我们对肠道病毒以及两种类型RNA重塑活性的理解。
