Molecular cloning and expression analysis of double-stranded RNA-dependent protein kinase (PKR) in rock bream (Oplegnathus fasciatus).

We have cloned and characterized rock bream double-stranded RNA-dependent protein kinase (PKR), which is a key component of type I IFN inducible innate immune system. Full-length rock bream PKR cDNA consists of 2115bp ORF encoding 704 amino acids, 124bp 5' UTR, and 529bp 3' UTR. Conserved domain analysis revealed that rock bream PKR contained two tandem dsRBM and kinase domain consisted of 11 kinase sub-motifs, which are characteristics found in other PKRs. Rock bream PKR was constitutively expressed in the spleen of rock bream and, upon injection of poly I:C, up-regulated not later than 12h post injection and returned to baseline level at 48h post injection. Although the eIF2alpha kinase activity of rock bream PKR was not examined in the present study, dsRNA inducible nature of rock bream PKR implies the possible important role of this gene in innate immune system of rock bream as suggested in zebrafish and flounder. Copyright 2009 Elsevier B.V. All rights reserved.