A type I crustin with an inhibitory effect on proteases and strong binding capacity to chitin from Neocaridina denticulata sinensis

· This study identifies a new crustin from Neocaridina denticulata sinensis , NdCrus1 · Both native and recombinant NdCrus1 appear to strongly bind chitin · Recombinant NdCrus1 does not inhibit growth of two bacterial pathogens · Recombinant NdCrus1 inhibits proteases under a wide range of temperatures Antimicrobial peptides (AMPs) are crucial immune effectors in the defense against pathogens. Crustins, small molecule antimicrobial peptides found in crustaceans, exhibit antimicrobial and antiviral properties, microbial binding ability, biofilm growth inhibition, and protease inhibition. In this study, we identify and characterize a crustin (named NdCrus1) from Neocaridina denticulata sinensis . The NdCrus1 was expressed in all tested tissues, with the highest expression in the stomach. NdCrus1 shares a high identity with type I crustins and contains a whey acidic protein (WAP) domain, featuring eight cysteine residues that form the conserved ‘‘four-disulfide core’’ structure. Recombinant NdCrus1 (rNdCrus1) did not significantly inhibit Bacillus subtilis and Vibrio parahaemolyticus but possessed an inhibitory effect on proteases under a wide range of temperature conditions. In addition, in vitro binding assays and molecular docking results indicated that NdCrus1 had a strong binding capacity with chitin. These results provide new insights into crustins in the life activities of N. denticulata sinensis and provide references for studying antibacterial activity characteristics and mechanisms in other crustaceans.