Translation enhancer in the 3'-untranslated region of rotavirus gene 6 mRNA promotes expression of the major capsid protein VP6.
The eleven rotavirus mRNAs contain 5'-cap structures and most end with the 3'-consensus sequence 5'-UGACC-3'. The UGACC functions as a common translation enhancer (3'-TE-con) that upregulates viral protein expression through a process mediated by the nonstructural protein NSP3. To address the possibility that gene-specific enhancers are also contained in the untranslated regions (UTRs) of the rotavirus mRNAs, we used rabbit reticulocyte lysates to investigate the translation efficiencies of analog RNAs containing viral-specific 5'-and 3'-UTRs and the open reading frame for chloramphenicol acetyltransferase. These experiments combined with the analysis of full-length viral RNAs and RNAs containing 3'-truncations showed that a highly active enhancer was present near the 5'-end of the 139-nucleotide 3'-UTR of the gene 6 mRNA (3'-TEg6). The 3'-TEg6 represents a functionally independent enhancer, as no other portion of the gene 6 mRNA was required for its activity. The 3'-TEg6 differs significantly from the 3'-TE-con in that the gene 6-specific enhancer does not require viral protein for activity and is formed by a sequence unique to only one of the eleven viral mRNAs. Together, our findings suggest that the 3'-UTR of the gene 6 mRNA contains two TEs, one is gene-specific (3'-TEg6) and the other is common to nearly all rotavirus genes (3'-TE-con). The activity of the 3'-TEg6 is likely important for directing the efficient translation of the gene 6 mRNA at levels sufficient to provide the 780 copies of VP6 necessary for the assembly of each progeny virion.
Yang
A-D
AD
Laboratory of Infectious Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Barro
M
M
Gorziglia
M I
MI
Patton
J T
JT
D020413:3' Untranslated Regions / Q000235:genetics*; D020121:5' Untranslated Regions / Q000235:genetics; D000956:Antigens, Viral; D001483:Base Sequence; D036022:Capsid Proteins / Q000235:genetics*; D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D017930:Genes, Reporter / Q000235:genetics; D005814:Genes, Viral / Q000235:genetics*; D014176:Protein Biosynthesis / Q000235:genetics*; D020871:RNA Stability; D012367:RNA, Viral / Q000235:genetics; D038621:Regulatory Sequences, Ribonucleic Acid / Q000235:genetics*; D012401:Rotavirus / Q000235:genetics*; D017384:Sequence Deletion / Q000235:genetics
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D000956:Antigens, Viral; D036022:Capsid Proteins; D012367:RNA, Viral; D038621:Regulatory Sequences, Ribonucleic Acid; C061332:VP6 protein, Rotavirus