The Atlantic salmon Z-DNA binding protein kinase phosphorylates translation initiation factor 2 alpha and constitutes a unique orthologue to the mammalian dsRNA-activated protein kinaseR

The translation initiation factor 2 alpha (eIF2 alpha )-kinase, dsRNA-activated protein kinase (PKR), constitutes one of the major antiviral proteins activated by viral infection of vertebrates. PKR is activated by viral double-stranded RNA and subsequently phosphorylates the alpha -subunit of trans...

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Published inThe FEBS journal Vol. 275; no. 1; pp. 184 - 197
Main Authors Bergan, Veronica, Jagus, Rosemary, Lauksund, Silje, Kileng, Oeyvind, Robertsen, Boerre
Format Journal Article
LanguageEnglish
Published 01.01.2008
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Summary:The translation initiation factor 2 alpha (eIF2 alpha )-kinase, dsRNA-activated protein kinase (PKR), constitutes one of the major antiviral proteins activated by viral infection of vertebrates. PKR is activated by viral double-stranded RNA and subsequently phosphorylates the alpha -subunit of translation initiation factor eIF2. This results in overall down regulation of protein synthesis in the cell and inhibition of viral replication. Fish appear to have a PKR-like protein that has Z-DNA binding domains instead of dsRNA binding domains in the regulatory domain, and has thus been termed Z-DNA binding protein kinase (PKZ). We present the cloning of the Atlantic salmon PKZ cDNA and show its upregulation by interferon in Atlantic salmon TO cells and poly inosinic poly cytodylic acid in head kidney. We also demonstrate that recombinant Atlantic salmon PKZ, expressed in Escherichia coli, phosphorylates eIF2 alpha invitro. This is the first demonstration that PKZ is able to phosphorylate eIF2 alpha . PKZ activity, as measured by phosphorylation of eIF2 alpha , was increased after addition of Z-DNA, but not by dsRNA. In addition, we show that wild-type Atlantic salmon PKZ, but not the kinase defective variant K217R, has a direct inhibitory effect on protein synthesis after transient expression in Chinook salmon embryo cells. Overall, the results support a role for PKZ, like PKR, in host defense against virus infection.
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ISSN:1742-464X
1742-4658
DOI:10.1111/j.1742-4658.2007.06188.x