tailieunhanh - Báo cáo khoa học: 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 kinase R

The translation initiation factor 2 alpha (eIF2a)-kinase, dsRNA-activated protein kinase (PKR), constitutes one of the major antiviral proteins activated by viral infection of vertebrates. PKR is activated by viral dou-ble-stranded RNA and subsequently phosphorylates thea-subunit of trans-lation initiation factor eIF2. | ỊFEBS Journal 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 kinase R Veronica Bergan1 Rosemary Jagus2 Silje Lauksund1 0yvind Kileng1 and B0rre Robertsen1 1 The Norwegian College of Fishery Science University of Tromso Norway 2 Center of Marine Biotechnology University of Maryland Biotechnology Institute Baltimore MD USA Keywords Atlantic salmon translation initiation factor 2 alpha phosphorylation protein kinase Z-DNA binding Correspondence B. Robertsen Department of Marine Biotechnology Norwegian College of Fishery Science University of Tromso N-9037 Tromso Norway Fax 47 776 46020 Tel 47 776 44487 E-mail Received 3 October 2007 revised 5 November 2007 accepted 12 November 2007 doi The translation initiation factor 2 alpha eIF2a -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 a-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 eIF2a in vitro. This is the first demonstration that PKZ is able to phosphorylate eIF2a. PKZ activity as measured by phosphorylation of eIF2a was increased after addition of Z-DNA but not by dsRNA. In addition we show that