Abstract
After entry into animal cells, most viruses hijack essential components involved in gene expression. This is the case of poliovirus, which abrogates cellular translation soon after virus internalization. Abrogation is achieved by cleavage of both eIF4GI and eIF4GII by the viral protease 2A. Apart from the interference of poliovirus with cellular protein synthesis, other gene expression steps such as RNA and protein trafficking between nucleus and cytoplasm are also altered. Poliovirus 2Apro is capable of hydrolyzing components of the nuclear pore, thus preventing an efficient antiviral response by the host cell. Here, we compare in detail poliovirus 2Apro with other viral proteins (from picornaviruses and unrelated families) as regard to their activity on key host factors that control gene expression. It is possible that future analyses to determine the cellular proteins targeted by 2Apro will uncover other cellular functions ablated by poliovirus infection. Further understanding of the cellular proteins hydrolyzed by 2Apro will add further insight into the molecular mechanism by which poliovirus and other viruses interact with the host cell.
Highlights
A great variety of animal viruses encode for proteases that accomplish crucial functions during the biological cycle of the virus [1]
Viruses reduce the genetic space occupied by 5 and 3 untranslated regions (UTRs), the signals devoted for mRNA transcription and to initiate translation are minimal, such that, for instance, in the case of picornaviruses or flaviviruses, only one 5 and 3 UTR is necessary for viral replication, transcription, translation, and morphogenesis, despite the fact that several viral proteins are synthesized by the infected cells
PV 2Apro has been very useful for examining the requirements for eIF4G to translate different cellular or viral mRNAs
Summary
A great variety of animal viruses encode for proteases that accomplish crucial functions during the biological cycle of the virus [1]. The main function of these proteases is to proteolyze viral polypeptide precursors to render mature viral proteins that form part of viral capsids or participate in virus vegetative processes [2] Both DNA and RNA viruses can encode proteases, the proteolytic tailoring of polypeptide precursors is most common among viruses with positive single-stranded RNA genomes, such as picornaviruses, flaviviruses, caliciviruses, and retroviruses [3,4,5,6,7]. Apart from generation of active viral proteins that participate in capsid morphogenesis and genome replication, viral proteases may target a number of cellular proteins Proteolysis of these cellular substrates can very much affect a variety of cellular processes and play an important role in virus-induced cytopathogenesis [8, 9]. The present paper focuses on the multifaceted activities of 2Apro and its regulation of different viral and cellular processes
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