Cloning and expression of selenoprotein W from pearl mussels Cristaria plicata

Selenoprotein W (SelW) is a selenocysteine containing protein with redox activity involved in the antioxidant response. In this study, a selenoprotein W was cloned from pearl mussel Cristaria plicata (designated as CpSelW), and the expression patterns were characterized in tissues after Aeromonas hydrophila challenged. The full-length cDNA of cpSelW was of 858 bp, containing a 5′ untranslated region (UTR) of 145 bp, a 3′ UTR of 455 bp with a poly (A) tail, and an open reading frame (ORF) of 258 bp encoding a polypeptide of 85 amino acids with the predicted molecular mass of 9.277 kDa, which shared 61% identity with SelW from Gallus gallus. A tertiary structure model generated for the CpSelW displayed a β-α-β-β-β-α secondary structure pattern, which was similar to mouse SelW protein 3D structure. The mRNA of CpSelW was constitutively expressed in tested tissues of healthy mussel, including mantle, gill, hemocytes, muscle, and hepatopancreas, and it was highly expressed in hepatopancreas. After mussels were stimulated by A. hydrophila, the mRNA expression of CpSelW in hemocytes at 6, 12 and 24 h, in gill at 12 h and in hepatopancreas at 24 h was significantly down-regulated.