Molecular cloning of a C-type lectin with one carbohydrate recognition domain from Fenneropenaeus merguiensis and its expression upon challenging by pathogenic bacterium or virus

• Single-CRD C-type lectin from Fenneropenaeus merguiensis is cloned and identified.
• Its gene is up-regulated upon challenging with pathogenic Vibrio harveyi or WSSV.
• This novel lectin may serve as a recognition molecule for microbial pathogens.

Lectins, one type of pattern recognition proteins, play important roles in an innate immunity of crustaceans including shrimp. A new C-type lectin designated FmLC1 was cloned from the hepatopancreas of banana shrimp Fenneropenaeus merguiensis by procedures of PCR and 5′ and 3′ rapid amplification of cDNA ends (RACE). The full-length cDNA is composed of 706 bp with a single open reading frame of 477 bp, encoding a peptide of 158 amino acid residues. Its deduced amino acid sequence comprises a putative signal peptide of 17 amino acids and has an estimated molecular mass of 17,934 Da with a theoretical pI of 4.46. The primary sequence of FmLC1 contains a single carbohydrate recognition domain (CRD) with an EPS (Glu-Pro-Ser) motif and one Ca2+ binding site, stabilized by two disulfide bonds. FmLC1 mRNA was detected to express specifically in the hepatopancreas, a master organ in shrimp. Its expression in the hepatopancreas was up-regulated to reach the maximum at 12 or 48 h following challenge of shrimp with Vibrio harveyi or white spot syndrome virus, respectively. These results suggest that FmLC1 may participate in recognition of invading pathogens such as bacteria and viruses, and play roles in the immune response of shrimp even at different stages of the clearance of pathogens.

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