Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications

Abstract

Background: Double-stranded (ds) RNA, generated during viral infection, binds and activates the mammalian anti-viral protein kinase PKR, which phosphorylates the translation initiation factor eIF2α leading to the general inhibition of protein synthesis. Although PKR-like activity has been described in fish cells, the responsible enzymes eluded molecular characterization until the recent discovery of goldfish and zebrafish PKZ, which contain Z-DNA-binding domains instead of dsRNAbinding domains (dsRBDs). Fish and amphibian PKR genes have not been described so far.

Phosphorylation of the NFAR proteins by the dsRNA-dependent protein kinase PKR constitutes a novel mechanism of translational regulation and cellular defense

“…3B). PKR homologs in zebrafish and X. laevis have been reported previously, and have been shown capable of phosphorylating yeast eIF2a on Ser 51 (Rothenburg et al 2008). Our data here demonstrate that CBTF 98 and CTBF 122 are phosphorylated on T188 and T315, perhaps by a X. laevis PKRhomolog, in response to virus infection, plausibly indicating a conserved mechanism of cellular antiviral host response.…”

“…Of interest is that T188 and T315 are evolutionarily conserved in CBTF 98 and CBTF 122 and undergo phosphorylation in response to virus infection. PKR homologs have been reported in amphibians (Rothenburg et al 2008). Thus, phosphorylation of CBTF 98 and CBTF 122 on T315 and T188 may have been evolutionarily conserved.…”

Literature review of baseline information to support the risk assessment of RNAi‐based GM plants

“…miRNA pathway is the dominant small RNA pathway while the existence and functionality of endogenous RNAi are unclear. Some variations (DNA-binding PKR homologs (Rothenburg et al, 2008)) were found in the interferon system, which is the main fish antiviral system. The present document has been produced and adopted by the bodies identified above as authors.…”

Molecular cloning, characterization and expression analysis of the PKZ gene in rare minnow Gobiocypris rarus

“…3). The kinase domains of fish PKR genes are more closely related to those of fish PKZ than to the PKR kinase domains of other vertebrate species [30]. The similarity in structure inferred the analogy in functions.…”

“…The similarity in structure inferred the analogy in functions. Both PKZ and PKR are present in zebrafish, and both of them can phosphorylate eIF2a in yeast [30]. In other fishes, either PKZ or PKR is reported.…”