The genome‐linked protein VPg of the Norwalk virus binds eIF3, suggesting its role in translation initiation complex recruitment

The positive‐strand RNA genomes of caliciviruses are not capped, but are instead covalently linked at their 5′ ends to a viral protein called VPg. The lack of a cap structure typical of eukaryotic mRNA and absence of an internal ribosomal entry site suggest that VPg may function in translation initi...

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Bibliographic Details
Published in:The EMBO journal 2003-06, Vol.22 (11), p.2852-2859
Main Authors: Daughenbaugh, Katie F., Fraser, Chris S., Hershey, John W.B., Hardy, Michele E.
Format: Article
Language:English
Subjects:
Animals
Base Sequence
calicivirus
Cell Line
EMBO23
EMBO31
Eukaryotic Initiation Factor-3 - metabolism
HeLa Cells
Humans
In Vitro Techniques
initiation factors
Mammals
Mutation
Norwalk virus - genetics
Norwalk virus - metabolism
Protein Binding
Protein Biosynthesis
Rabbits
Recombinant Fusion Proteins - genetics
Recombinant Fusion Proteins - metabolism
RNA Caps - genetics
RNA Caps - metabolism
RNA virus
RNA, Viral - genetics
RNA, Viral - metabolism
translation initiation
Viral Core Proteins - genetics
Viral Core Proteins - metabolism
VPg
Yeasts
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Summary:The positive‐strand RNA genomes of caliciviruses are not capped, but are instead covalently linked at their 5′ ends to a viral protein called VPg. The lack of a cap structure typical of eukaryotic mRNA and absence of an internal ribosomal entry site suggest that VPg may function in translation initiation on calicivirus RNA. This hypothesis was tested by analyzing binding of Norwalk virus VPg to translation initiation factors. The eIF3d subunit of eIF3 was identified as a binding partner of VPg by yeast two‐hybrid analysis. VPg bound to purified mammalian eIF3 and to eIF3 in mammalian cell lysates. To test the effects of the VPg–eIF3 interaction on translation, VPg was added to cell‐free translation reactions programmed with either capped reporter RNA, an RNA containing an EMCV internal ribosomal entry site (IRES) or an RNA with a cricket paralysis virus IRES. VPg inhibited translation of all reporter RNAs in a dose‐dependent manner. Together, the data suggest that VPg may play a role in initiating translation on calicivirus RNA through unique protein–protein interactions with the translation machinery.
ISSN:0261-4189
1460-2075
DOI:10.1093/emboj/cdg251