N ⁶-methyladenosine modification and METTL3 modulate enterovirus 71 replication

Abstract

N ⁶-methyladenosine (m ⁶A) constitutes one of the most abundant internal RNA modifications and is critical for RNA metabolism and function. It has been previously reported that viral RNA contains internal m ⁶A modifications; however, only recently the function of m ⁶A modification in viral RNAs has been elucidated during infections of HIV, hepatitis C virus and Zika virus. In the present study, we found that enterovirus 71 (EV71) RNA undergoes m ⁶A modification during viral infection, which alters the expression and localization of the methyltransferase and demethylase of m ⁶A, and its binding proteins. Moreover, knockdown of m ⁶A methyltransferase resulted in decreased EV71 replication, whereas knockdown of the demethylase had the opposite effect. Further study showed that the m ⁶A binding proteins also participate in the regulation of viral replication. In particular, two m ⁶A modification sites were identified in the viral genome, of which mutations resulted in decreased virus replication, suggesting that m ⁶A modification plays an important role in EV71 replication. Notably, we found that METTL3 interacted with viral RNA-dependent RNA polymerase 3D and induced enhanced sumoylation and ubiquitination of the 3D polymerase that boosted viral replication. Taken together, our findings demonstrated that the host m ⁶A modification complex interacts with viral proteins to modulate EV71 replication.