Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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5' Untranslated Regions / genetics
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5' Untranslated Regions / metabolism
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Animals
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Base Sequence
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Cell Line
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Enzyme Activation
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Eukaryotic Initiation Factor-2 / genetics
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Eukaryotic Initiation Factor-2 / metabolism
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Gene Expression Regulation, Enzymologic / genetics*
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Humans
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Interferon-gamma / genetics*
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Interferon-gamma / metabolism
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Molecular Sequence Data
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Mutation
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Nucleic Acid Conformation*
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Phosphorylation
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Protein Binding
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Protein Biosynthesis*
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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eIF-2 Kinase / genetics
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eIF-2 Kinase / metabolism*
Substances
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5' Untranslated Regions
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Eukaryotic Initiation Factor-2
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RNA, Messenger
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Interferon-gamma
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eIF-2 Kinase
Associated data
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GENBANK/AF126247
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GENBANK/J00207
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GENBANK/J00219
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GENBANK/J02645
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GENBANK/K00083
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GENBANK/L37782
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GENBANK/M35663
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GENBANK/S63967
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GENBANK/U04050
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GENBANK/V00534
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GENBANK/X02325
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GENBANK/X64659
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GENBANK/X69198
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GENBANK/Z54144