A novel C-type lectin from Crassostrea gigas involved in the innate defense against Vibrio alginolyticus.

Abstract C-type lectins (CTLs) are important immune molecules that participate in invertebrate defense response. In the present work, a novel structural CTL (CgLec-4E) was identified from Crassostrea gigas, which encodes 237 amino acids (aa) with an extra long chain of aa and in the C-type CRD domain with EPA, QPG and WHD mutated motifs respectively. rCgLec-4E could agglutinate and inhibit the growth of Vibrio alginolyticus, except Chlorella, which might be relevant to three mutated motifs. CgLec-4E was mainly expressed in digestive gland, and its expression level was significantly up-regulated post V. alginolyticus challenge, indicating that the high expression of CgLec-4E could provide necessary mucosal immune protections and might involve in food particle recognition for C. gigas. Moreover, the subcellular locations indicated that CgLec-4E might play different roles in the immune response. Taken together, our results enrich our understanding of the structures and function of CTLs in invertebrates.