CAMS Key Laboratory of Antiviral Drug Research, Beijing Key Laboratory of Antimicrobial Agents, NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
J Virol. 2024 Oct 22;98(10):e0133524. doi: 10.1128/jvi.01335-24. Epub 2024 Aug 30.
Ubiquitin modification of viral proteins to degrade or regulate their function is one of the strategies of the host to resist viral infection. Here, we report that ubiquitin protein ligase E3C (UBE3C), an E3 ubiquitin ligase, displayed inhibitory effects on EV-A71 replication. UBE3C knockdown resulted in increased viral protein levels and virus titers, whereas overexpression of UBE3C reduced EV-A71 replication. To explore the mechanism by which UBE3C affected EV-A71 infection, we found that the C-terminal of UBE3C bound to 2C protein and facilitated K33/K48-linked ubiquitination degradation of 2C K268. Moreover, UBE3C lost its ability to degrade 2C K268R and had a diminished inhibitory impact against the replication of recombinant EV-A71-FY-2C K268R. In addition, UBE3C also promoted ubiquitination degradation of the 2C protein of CVB3 and CVA16 and inhibited viral replication. Thus, our findings reveal a novel mechanism that UBE3C acts as an enterovirus host restriction factor, including EV-A71, by targeting the 2C protein.
The highly conserved 2C protein of EV-A71 is a multifunctional protein and plays a key role in the replication cycle. In this study, we demonstrated for the first time that UBE3C promoted the degradation of 2C K268 K33/K48-linked ubiquitination, thereby inhibiting viral proliferation. Our findings advance the knowledge related to the roles of 2C in EV-A71 virulence and the ubiquitination pathway in the host restriction of EV-A71 infection.
泛素修饰病毒蛋白以降解或调节其功能是宿主抵抗病毒感染的策略之一。在这里，我们报告泛素蛋白连接酶 E3C（UBE3C），一种 E3 泛素连接酶，对 EV-A71 复制显示出抑制作用。UBE3C 的敲低导致病毒蛋白水平和病毒滴度增加，而 UBE3C 的过表达则降低了 EV-A71 的复制。为了探索 UBE3C 影响 EV-A71 感染的机制，我们发现 UBE3C 的 C 端与 2C 蛋白结合，并促进 2C K33/K48 连接泛素化降解 K268。此外，UBE3C 失去了降解 2C K268R 的能力，并且对重组 EV-A71-FY-2C K268R 的复制抑制作用减弱。此外，UBE3C 还促进了 CVB3 和 CVA16 的 2C 蛋白的泛素化降解，并抑制了病毒复制。因此，我们的研究结果揭示了一种新的机制，UBE3C 通过靶向 2C 蛋白作为肠道病毒宿主限制因子，包括 EV-A71。
EV-A71 的高度保守的 2C 蛋白是一种多功能蛋白，在复制周期中起着关键作用。在这项研究中，我们首次证明 UBE3C 促进了 2C K268 的降解，K33/K48 连接的泛素化，从而抑制了病毒的增殖。我们的发现推进了与 2C 在 EV-A71 毒力中的作用以及泛素化途径在 EV-A71 感染的宿主限制中的相关知识。
