Immune characterization and expression analysis of a C-type lectin from Pinctada fucata martensii

C-type lectins are involved in nonself-recognition and pathogen clearance, and play an important role in innate immunity. Pinctada fucata martensii, which is an important shellfish in the pearl industry, is being attacked by pathogenic microorganisms; therefore, it is urgent to study its innate immune function. In the present study, a C-type lectin (designated as Pmlectin) containing two carbohydrate-recognition domains was identified in P. f. martensii. The open reading frame of Pmlectin encodes 293 amino acids and Pmlectin expression was detected in various tissues, with the highest expression being in the gill. Pathogen-associated molecular patterns, as stimulated by lipopolysaccharides, peptidoglycan and polyinosinic acid, could induce the expression of Pmlectin. Meanwhile, a recombinant protein of Pmlectin (rPmlectin) was used for antibacterial function analysis, and the rPmlectin was shown to be bacteriostatic against Aeromonas hydrophila and Pseudomonas aeruginosa. Overall, the results of this study provide evidence for understanding the diversity of C-type lectins in P. f. martensii. In particular, Pmlectin was shown to be involved in the innate immune response P. f. martensii.