The RNA-dependent RNA polymerase of enterovirus A71 associates with ribosomal proteins and positively regulates protein translation

Enteroviruses, which may cause neurological complications, have become a public health threat worldwide in recent years. Interactions between cellular proteins and enteroviral proteins could interfere with cellular biological processes to facilitate viral replication in infected cells. Enteroviral RNA-dependent RNA polymerase (RdRP), known as 3D protein, mainly functions as a replicase for viral RNA synthesis in infected cells. However, the 3D protein encoded by enterovirus A71 (EV-A71) could also interact with several cellular proteins to regulate cellular events and responses during infection. To globally investigate the functions of the EV-A71 3D protein in regulating biological processes in host cells, we performed immunoprecipitation coupled with liquid chromatography−tandem mass spectrometry (LC-MS/MS) to identify host proteins that may associate with the 3D protein. We found that the 3D protein interacts with factors involved in translation-related biological processes, including ribosomal proteins. In addition, polysome profiling analysis showed that the 3D protein cosediments with small and large subunits of ribosomes. We further discovered that the EV-A71 3D protein could enhance EV-A71 internal ribosome entry site (IRES)-dependent translation as well as cap-dependent translation. Collectively, this research demonstrated that the RNA polymerase encoded by EV-A71 could join a functional ribosomal complex and positively regulate viral and host translation.

近年来，可引发神经系统并发症的肠道病毒已成为全球公共卫生威胁。细胞蛋白与肠病毒蛋白之间的相互作用可干扰细胞生物学过程，从而促进感染细胞内的病毒复制。肠道病毒的RNA依赖的RNA聚合酶（RNA-dependent RNA polymerase, RdRP）即3D蛋白，其主要功能是在感染细胞中作为复制酶参与病毒RNA的合成。然而，肠道病毒A71（enterovirus A71, EV-A71）编码的3D蛋白还可与多种细胞蛋白相互作用，以调控感染过程中的细胞事件与应答反应。为全面探究EV-A71 3D蛋白在调控宿主细胞生物学过程中的功能，我们采用免疫共沉淀联合液相色谱-串联质谱（liquid chromatography−tandem mass spectrometry, LC-MS/MS）技术，筛选可与3D蛋白结合的宿主蛋白。研究发现，3D蛋白可与参与翻译相关生物学过程的因子（包括核糖体蛋白）相互作用。此外，多聚核糖体谱分析结果显示，3D蛋白可与核糖体的大小亚基共沉降。我们进一步证实，EV-A71 3D蛋白既可增强EV-A71内部核糖体进入位点（internal ribosome entry site, IRES）依赖型翻译，也可增强帽依赖型翻译。综上，本研究证明，EV-A71编码的RNA聚合酶可结合功能性核糖体复合物，并正向调控病毒与宿主的翻译过程。