Antibacterial activity of four recombinant carbohydrate recognition domain proteins identified from the kuruma shrimp Marsupenaeus japonicus.

The carbohydrate recognition domain (CRD) is the key component of C-type lectins (CTLs) with the capacity to recognize and eliminate invading pathogens. Herein, the recombinant proteins of four CRDs identified from the kuruma shrimp, Marsupenaeus japonicus, were produced and purified by an Escherichia coli expression system and affinity chromatography. Bacterial binding and antibacterial assays showed that the four CRDs displayed various bacterial binding and antibacterial activities against different bacteria. Among the four recombinant CRDs, His-CRD2-3 exhibited the broadest spectrum of bacterial binding and antibacterial activities against gram-negative bacteria (Vibrio parahaemolyticus, V. alginolyticus and V. harveyi) and gram-positive bacteria (Staphylococcus aureus and Micrococcus lysodeikticus). Moreover, the four recombinant CRDs showed different capacities to regulate the expression of several immune effector genes (MjCTL3, MjCTL4, MjCTL, Mjily and Mjsty), among which His-CRD2-3 displayed broader and stronger inductive effects on these immune effector genes. This study indicated that the four CRDs participated in immune defense by binding and killing bacteria and regulating the transcription of other immune effector genes. In addition, our results suggested that His-CRD2-3 might be a promising agent for the prevention and treatment of bacteriosis.