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范围内的公共卫生威胁。宿主细胞蛋白与肠道病毒蛋白之间的相互作用，可干扰宿主细胞的生物学进程，进而促进受感染细胞内的病毒复制。肠道病毒RNA依赖的RNA聚合酶（RNA-dependent RNA polymerase，RdRP）又称3D蛋白，在受感染细胞中主要作为病毒RNA合成的复制酶发挥功能。然而，肠道病毒A71（enterovirus A71，EV-A71）编码的3D蛋白，在感染过程中还可与多种宿主细胞蛋白相互作用，调控宿主细胞的生命活动与应答反应。为全面探究EV-A71 3D蛋白在调控宿主细胞生物学进程中的功能，本研究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，鉴定可与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进程的因子相互作用，其中包括核糖体蛋白。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。本研究进一步证实，EV-A71 3D蛋白可同时增强EV-A71内部核糖体进入位点（internal ribosome entry site，IRES）依赖型翻译与帽依赖型翻译。综上，本研究表明，EV-A71编码的RNA聚合酶可整合入功能性核糖体复合物，并正向调控病毒与宿主的翻译过程。