Molecular characterization and expression analysis of Lily-type lectin ( Sm LTL) in turbot Scophthalmus maximus , and its response to Vibrio anguillarum

A full-length lily-type lectin (SmLTL) was identified from turbot (Scophthalmus maximus) in this study. By searching database for protein identification and function prediction, SmLTL were confirmed. The full-length cDNA of SmLTL is composed of 569 bp and contains a 339 bp ORF that encodes 112 amino acid residues. The SmLTL peptide is characterized by a specific β-prism architecture and contains three mannose binding sites in a three-fold internal repeat between amino acids 30–99; two of the repeats share the classical mannose binding domain (QxDxNxVxY) while the third binding site was similar to other fish-specific binding motifs (TxTxGxRxV). The primary, secondary, and tertiary structures of SmLTL were predicted and analyzed, indicating that the SmLTL protein was hydrophilic, contained 5.36% α-helices, 39.29% extended strands, 16.07% β-folds, and 39.29% random coils, and three β-folds. Quantitative realtime polymerase chain reaction (qPCR) analysis revealed that the SmLTL mRNA was abundantly expressed in skin, gill, and intestine. Low levels of SmLTL expression were observed in other tissues. The expression of SmLTL in gill, skin and intestine increased at mRNA level after stimulation of Vibrio anguillarum, our results suggest that SmLTL serve as the first line of defence against microbial infections and play a pivotal role in the innate mucosal immune system. The current study indicates that SmLTL is a member of the lilytype lectin family and the information reported here will provide an important foundation for future research on the role of this protein.