In enteroviruses, the inhibition of protein synthesis from capped host cell mRNA is catalyzed by the virally encoded 2A proteinase (2Apro), which cleaves eukaryotic initiation factors (eIF) 4GI and 4GII. Despite much investigation, the exact mechanism of 2Apro cleavage remains however unclear. Here, we identify the domains responsible for the eIF4E/HRV2 2Apro interaction using molecular modelling and describe mutations that impair this interaction and delay in vitro cleavage of eIF4G isoforms. Furthermore, we produced HRV1A viruses bearing the mutation L17R, Y32A or Y86A in the 2Apro sequence. All three viruses showed reduced yield and were appreciably delayed during infection in eIF4GI cleavage. Thus, we propose for genetic group A HRVs that the eIF4E/2Apro interaction is essential for successful viral replication. In contrast, HRV4 2Apro and coxsackievirus B4 2Apro failed to form complexes with eIF4E, suggesting that the mechanism of eIF4G isoform cleavage in these and related viruses is different.
Keywords: Cap-binding protein; Chymotrypsin-like cysteine proteinase; Host cell shut-off; Initiation of protein synthesis; Protein-protein interactions; Virus-host interactions.
Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.