MOLECULAR CHARACTERIZATION AND INSIGHTS INTO LIVE PATHOGENIC STRESS OF TWO MICROSOMAL GLUTATHIONE S-TRANSFERASE ISOFORMS FROM BLACK ROCKFISH (Sebastes schlegeli)

Glutathione S-transferases (GSTs) are a class of enzymes that facilitate the detoxification of injurious electrophiles in phase II metabolism identified in almost all the kingdoms. Since they have grouped in to three distinct super families, their functions and capabilities are varied. In this study, responses upon live pathogenic stress of two microsomal GST (mGST) isoforms from black rockfish (Sebastes schlegeli) to be investigated.

Previously constructed rockfish cDNA library was used to identify the full-length cDNA sequences of two mGST isoforms (RfmGSTI and RfmGSTII) and characterized at molecular level. Their potential role in immunity was observed via challenging them with Streptococcus iniae and Poly I:C.

In silico analysis of both isoforms revealed their typical domain architecture. Open reading frame (ORF) of RfmGSTI cDNA was 462 bp long which encodes a protein of 153 amino acids (aa) with 17 kD molecular weight. ORF of RfmGSTII cDNA was 423 bp long which encodes a protein of 140 aa with 16 kD molecular weight. In phylogenetic analysis, both isoforms were claded with their fish counterparts. Both isoforms were highly expressed in liver as well as blood under physiological conditions. Challenge experiment results showed that both isoforms could be up-regulated with the pathogenic invasions. According to the results, it could be suggested that both isoforms are involved in immunity of black rockfish protecting them from pathogenic invasions.