Fish lily type lectin-1 contains β-prism architecture: Immunological characterization

- CsLTL-1 identified from cDNA library of Channa striatus.
- It contains a mannose binding site.
- CsLTL-1 highly expressed in gills and is up-regulated by fungus and bacteria.
- Recombinant CsLTL-1 agglutinates erythrocytes in a calcium independent manner.
- d-Mannose (50 mM) and d-glucose (100 mM) inhibited the agglutination of CsLTL-1.

In this study we report a full-length lily type lectin-1 (CsLTL-1) identified from striped murrel, Channa striatus. CsLTL-1 was identified from the established C. striatus cDNA library using GS-FLX™ genome sequencing technology and was found to contain 354 nucleotide base pairs and its open reading frame (ORF) encodes a 118 amino acid residue. CsLTL-1 mRNA is predominately expressed in the gills and is up-regulated upon infection with fungus (Aphanomyces invadans) and bacteria (Aeromonas hydrophila). Hemagglutination studies with recombinant CsLTL-1 show that, at 4 μg/ml agglutinates occurs in a calcium independent manner and is inhibited in the presence of d-mannose (50 mM) and d-glucose (100 mM). The CsLTL-1 sequence was completely characterized using various bioinformatics tools. CsLTL-1 peptide contains a mannose binding site at 30-99 along with its specific motif of β-prism architecture. The phylogenetic analysis showed that CsLTL-1 clustered together with LTL-1 from Oplegnathus fasciatus. CsLTL-1 protein 3D structure was predicted by I-Tasser program and the model was evaluated using Ramachanran plot analysis. The secondary structure analysis of CsLTL-1 reveals that the protein contains 23% β-sheets and 77% coils. The overall results showed that CsLTL-1 is an important immune gene involved in the recognition and elimination of pathogens in murrels.