Identification and functional characterization of CL-11 in black rockfish (Sebastes schlegelii)

CL-11 (Collectin-11, also known as Collectin kidney-1 or CL-K1) is a member of collectin family that works as a pattern recognition molecule (PRM) and participating in lectin-complement pathway in host defense against pathogens. We identified the CL-11 homologue SsCL-11 in black rockfish ( Sebastes schlegelii ) and investigated the functional characteristics in this study. The SsCL-11 has conserved protein modules, i.e. an N-terminal hydrophobic region, a collagen-like region, an α-helical neck region and a carbohydrate recognition domain (CRD). SsCL-11 has varying degrees of expressions in difference tissues, among which the highest expression is observed in liver. It also shows induced expressions in immune-related tissues following Aeromonas salmonicida ( A. salmonicida ) infection. In addition, SsCL-11 exhibits binding abilities to different kinds of carbohydrates, pathogen-associated molecular patterns (PAMPs) and bacteria. It exhibits comparatively strong binding to l -fucose, d -mannose, and d -glucose, which is consistent with the functional EPN motif in its CRD. SsCL-11 also shows agglutinating effects on various bacteria in the presence of Ca 2+ . Furthermore, SsCL-11 is confirmed to be a secretory lectin and can form multimers. These findings collectively demonstrate that SsCL-11 can function as a recognition molecule in pathogen resistance in black rockfish, which will promote our understanding of immunological roles of fish collectins. • SsCL-11 is a secretory protein. • SsCL-11 can bind carbohydrates, PAMPs and pathogenic bacteria in a dose-dependent manner. • SsCL-11 can agglutinate bacteria in the presence of Ca 2+ . • SsCL-11 can form multimers.