Enteroviral 3C protease cleaves N4BP1 to impair the host inflammatory response

Targeting cellular proteins for cleavage by enteroviral 3Cpro is a conserved strategy used by enteroviruses to promote viral replication. While the cleavage of certain host proteins by 3Cpro may not affect viral replication, it is strongly associated with the pathogenesis of viral infection. In this study, we identified and characterized N4BP1, which plays such a role, using a combination of bioinformatic, biochemical, and cell biological approaches. Our data show that multiple 3Cpros cleave N4BP1 at residue Q816 and that cleavage of endogenous N4BP1 can occur during viral infection. N4BP1 has no effect on coxsackievirus B3 replication, but 3Cpro-induced N4BP1 cleavage abolishes its regulatory function in NF-κB signaling. We also show that mouse N4bp1 resists human enteroviral 3Cpro cleavage. In contrast, rodent enteroviral EMCV 3Cpro can target human and mouse N4BP1 for cleavage at different residues, which indicates that future investigations are needed to elucidate the potential mechanisms involved.