Human interferon-gamma mRNA autoregulates its translation through a pseudoknot that activates the interferon-inducible protein kinase PKR.
PKR, an interferon (IFN)-inducible protein kinase activated by double-stranded RNA, inhibits translation by phosphorylating the initiation factor eIF2alpha chain. We show that human IFN-gamma mRNA uses local activation of PKR in the cell to control its own translation yield. IFN-gamma mRNA activates PKR through a pseudoknot in its 5' untranslated region. Mutations that impair pseudoknot stability reduce the ability to activate PKR and strongly increase the translation efficiency of IFN-gamma mRNA. Nonphosphorylatable mutant eIF2alpha, knockout of PKR and PKR inhibitors 2-aminopurine, transdominant-negative PKR, or vaccinia E3L correspondingly enhances translation of IFN-gamma mRNA. The potential to form the pseudoknot is phylogenetically conserved. We propose that the RNA pseudoknot acts to adjust translation of IFN-gamma mRNA to the PKR level expressed in the cell.
Ben-Asouli
Yitzhak
Y
Department of Molecular Virology, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
Banai
Yona
Y
Pel-Or
Yehuda
Y
Shir
Alexei
A
Kaempfer
Raymond
R
D020121:5' Untranslated Regions / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004789:Enzyme Activation; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010766:Phosphorylation; D011485:Protein Binding; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism*
D020121:5' Untranslated Regions; D015852:Eukaryotic Initiation Factor-2; D012333:RNA, Messenger; D007371:Interferon-gamma; D019892:eIF-2 Kinase