Abstract
The eukaryotic initiation factor 4A (eIF4A) is a DEAD box helicase that unwinds RNA structure in the 5′ untranslated region (UTR) of mRNAs. Here, we investigated the role of eIF4A in porcine sapovirus VPg-dependent translation. Using inhibitors and dominant-negative mutants, we found that eIF4A is required for viral translation and infectivity, suggesting that despite the presence of a very short 5′ UTR, eIF4A is required to unwind RNA structure in the sapovirus genome to facilitate virus translation.
Highlights
The eukaryotic initiation factor 4A is a DEAD box helicase that unwinds RNA structure in the 5= untranslated region (UTR) of mRNAs
Eukaryotic initiation factor 4F, comprised of eIF4E, eukaryotic initiation factor 4A (eIF4A), and eIF4G, is essential for initiation of cellular protein synthesis [1]. eIF4E binds the cap structure on the 5= end of mRNAs, while eIF4A, an RNA helicase, unwinds secondary structure in the 5= untranslated region (UTR), facilitating ribosomal recruitment [1]. eIF4G coordinates the assembly of the eIF4F complex and the recruitment of additional eIFs [1, 2]
The functional roles of the components of the eIF4F complex differ among caliciviruses [3]; VPg from all three viruses binds directly to eIF4E, but eIF4E is required only for porcine sapovirus (PSaV) and feline calicivirus (FCV) viral RNA translation and infectivity, but not those of murine norovirus (MNV) [3, 4, 6]
Summary
The eukaryotic initiation factor 4A (eIF4A) is a DEAD box helicase that unwinds RNA structure in the 5= untranslated region (UTR) of mRNAs. The VPg proteins of feline calicivirus (FCV), murine norovirus (MNV), and porcine sapovirus (PSaV) interact with the eIF4F complex in infected cells [3, 4, 6]. The functional roles of the components of the eIF4F complex differ among caliciviruses [3]; VPg from all three viruses binds directly to eIF4E, but eIF4E is required only for PSaV and FCV viral RNA translation and infectivity, but not those of MNV [3, 4, 6].
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