A galectin with quadruple-domain from red abalone Haliotis rufescens involved in the immune innate response against to Vibrio anguillarum

Galectins are proteins that recognize and bind specifically β-galactosidase residues, playing important roles in the innate immune response of vertebrates and invertebrates. The cDNA of a tandem repeat galectin from the red abalone Haliotis rufescens cDNA (HrGal) was cloned and characterized using rapid amplification of cDNA end technique. The full-length cDNA of HrGal was 2471 bp, with a 5ʹ terminal untranslated region (UTR) of 131 bp, a 3ʹ UTR of 672 pb, and an open reading frame (ORF) of 1668 bp encoding a polypeptide of 556 amino acid. The ORF contains four domains carbohydrate recognition (CRD) with typical conserved motifs, which are important for carbohydrate recognition, and it appear to posses neither a signal peptide nor a transmembrane domain. The deduced amino acid sequence and the multi-domain organization of HrGal were highly similar to those described for other tandem repeat galectins of invertebrate organisms. Quantitative real time PCR analyses indicated that HrGal mRNA was highly expressed in hemocytes and gills tissues. The temporal expression of HrGal mRNA in hemocytes challenged to Vibrio anguillarum was time-dependent, showing u-regulation at 32 h post challenge. The results suggest that HrGal may be involved in the immune innate response against bacterial infection.