cDNA cloning and mRNA expression of four glutathione S-transferase (GST) genes from Mytilus galloprovincialis

Glutathione S-transferases (GSTs) are phase II enzymes involved in the regulation of redox homeostasis and innate immune responses against bacterial infection, which also play important roles in the detoxification of xenobiotics. In this study, we reported four genes of the GST family (named MgGSTα, MgGSTS1, MgGSTS2, and MgGSTS3, respectively) from Mytilus galloprovincialis. MgGSTα, MgGSTS1, MgGSTS2, and MgGSTS3 consisted of open reading frame (ORF) of 648 bp, 612 bp, 621 bp and 609 bp respectively, which encoded proteins of 216, 204, 207 and 203 amino acids residues, respectively. Sequence analysis showed that the predicted protein sequence of MgGSTs contained the conserved domain of the GST_N and GST_C. Alignment analysis indicated that the MgGSTs were divided into two types, one was of alpha GST, and the others were of sigma class. Tissue distribution study revealed that MgGSTα, MgGSTS2, MgGSTS3 transcripts were highly expressed in hemocytes, while MgGSTS1 mRNA was most abundantly expressed in hepatopancreas. After bacterial challenge, the expression level of these MgGSTs in hemocytes were all significantly higher than that of the control group. These results suggested that MgGSTs might play important roles in the modulation of immune response in M. galloprovincialis.