Molecular characterization and expression analysis of double‐stranded RNA‐dependent protein kinase (PKR) in Dabry's sturgeon (Acipenser dabryanus).

Protein kinase RNA‐activated (PKR) is an important component of the innate immune system induced by interferon. This antiviral protein senses a variety of stresses and pathogen‐driven double‐stranded RNAs (dsRNAs). In the present study, we cloned and characterized the PKR gene from Dabry's sturgeon (Acipenser dabryanus). Bioinformatics analysis revealed that the AdPKR gene comprises a coding sequence (CDS) of 1848 bp, encoding a 616 amino acids (aa) polypeptide. AdPKR shares high aa identity/similarity with proteins from other fish, ranging from 33.4%/51.8% to 87.6%/91.2%, and relatively low aa identity (13.9%) and similarity (26.8%) with human PKR. The AdPKR polypeptide has two dsRNA‐binding motifs at the N‐terminus and a conserved catalytic kinase domain at the C‐terminus. The sturgeon PKR gene contains 17 exons split by 16 introns. Phylogenetic analysis clustered AdPKR together with its counterparts from other teleost fishes. Real‐time fluorescene quantitative PCR (RT‐qPCR) transcription profiles revealed highest AdPKR expression levels in brain, followed by middle kidney, skin, muscle and head kidney. AdPKR mRNA transcripts were significantly increased at 6 hr post‐stimulation (hps) with polyinosinic:polycytidylic acid (poly I:C), remained high at 24 hps, then decreased to normal levels at 48 hps. These results indicate that AdPKR might play a vital role in antiviral immune responses. [ABSTRACT FROM AUTHOR]