Comparative study of two single CRD C-type lectins, CgCLec-4 and CgCLec-5, from pacific oyster Crassostrea gigas

• Published in: Fish & Shellfish Immunology
• Main Authors: Jia, Zhihao, Zhang, Huan, Jiang, Shuai, Wang, Mengqiang, Wang, Lingling, Song, Linsheng
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Crassostrea Gigas; Innate Immunity; Lectin; Recognition; Antimicrobial Activity; Pacific; Crassostrea gigas; Pacific oyster
• Online Access: http://ir.qdio.ac.cn/handle/337002/136238; https://doi.org/10.1016/j.fsi.2016.10.030

C-type lectins (CTLs), a superfamily of Cat(2+)-dependent carbohydrate-recognition proteins, are involved in nonself-recognition and pathogen elimination, and play crucial roles in the innate immunity. In the present study, two single CRD C-type lectins, CgCLec-4 and CgCLec-5, were identified from oyster Crassostrea gigas. The open reading frame (ORF) of CgCLec-4 and CgCLec-5 encoded polypeptides of 152 and 150 amino acids, respectively. Both CgCLec-4 and CgCLec-5 contained one CRD with six conserved cysteines to form three disulfide bridges. The motif in Ca2+-binding site 2 of CgCLec-4 was QPE, while it was QYE, a non-a typical motif in CgCLec-5. CgCLec-4 was a secreted lectin with a signal peptide which was highly expressed in hepatopancreas, mantle and hemocytes. CgCLec-5 was an intracellular lectin which was mostly expressed in hemocytes. The lipopolysaccharide stimulation could induce the expressions of CgCLec-4 and CgCLec-5. The recombinant proteins of CgCLec-4 and CgCLec-5 (rCgCLec-4 and rCgCLec-5) could bind to various PAMPs including LPS, PGN, GLU and mannan, while the binding affinity of rCgCLec-5 was stronger than that of rCgCLec-4. Meanwhile, rCgCLec-4 and rCgCLec-5 could bind to different kinds of microorganisms, including Staphylococcus aureus, Escherichia coli and Vibro anguillarum and Yarrowia lipolytica, and the microbial agglutinating ability of rCgCLec-4 was stronger than that of CgCLec-5. Moreover, rCgCLec-4 exhibited anti-microbial activity against bacteria and fungi, but antimicrobial activity of CgCLec-5 was not obvious. All these results suggested that CgCLec-4 and CgCLec-5 could function as an important PRR involved in immune defense against invading pathogen in oyster, and the diversity and complexity of motifs in Ca2+ binding site 2 in CRDs determined their comprehensive recognition spectrum and multiple immune functions. (C) 2016 Elsevier Ltd. All rights reserved.