A DM9-containing protein from oyster Crassostrea gigas (CgDM9CP-2) serves as a multipotent pattern recognition receptor

• Published in: Developmental & Comparative Immunology
• Main Authors: Liu, Yu, Zhang, Peng, Wang, Weilin, Dong, Miren, Wang, Min, Gong, Changhao, Jia, Zhihao, Liu, Zhaoqun, Zhang, Anguo, Wang, Lingling, Song, Linsheng
• Format: Report
• Language: English
• Published: ELSEVIER SCI LTD 2018
• Subjects: Crassostrea gigas; DM9 domain; Pattern recognition receptor; Mannose binding; Antimicrobial activities; Fisheries; Immunology; Zoology; Pacific; Pacific oyster
• Online Access: http://ir.qdio.ac.cn/handle/337002/158993; http://ir.qdio.ac.cn/handle/337002/158994; https://doi.org/10.1016/j.dci.2018.03.003

DM9 is a novel protein domain with unknown function originally discovered in Drosophila melanogaster. Recently, a protein harboring DM9 repeats was identified as mannose-specific lectin (CgCGL1, renamed as CgDM9CP-1) from the Pacific oyster Crassostrea gigas. In the present study, another DM9 containing protein was identified from oyster C. gigas (designated as CgDM9CP-2). The open reading frame of CgDM9CP-2 gene was of 432 bp, encoding a polypeptide of 143 amino acids with two tandem DM9 repeats. The deduced amino acid sequence of CgDM9CP-2 shared 60.8% identity with that of CgDM9CP-1. In the unrooted phylogenetic tree, CgDM9CP-2 was closely clustered with CgDM9CP-1, and then assigned into the branch of invertebrate DM9CPs. The mRNA transcripts of CgDM9CP-2 were expressed in all the tested tissues, including mantle, gonad, gills, adductor muscle, hemocytes, and hepatopancreas, with the highest expression level in gills. CgDM9CP-2 protein was mainly distributed on the cytomembrane of oyster hemocytes. After mannose stimulation, the mRNA expression of CgDM9CP-2 in gills was up regulated to the peak level (5.90-fold of that in SSW group, p < 0.05) at 24 h, and kept at a significantly higher level compared with that in control group at 6-48 h. It significantly increased at 6 h (2.33-fold, p <0.05), and 12 h (3.08-fold, p <0.05) post Vibrio splendidus stimulation, and then gradually decreased from 48 to 72 h (p < 0.05) with significant difference comparing with that in control group. The recombinant CgDM9CP-2 protein (rCgDM9CP-2) displayed higher binding affinity to D-(+)-mannose while lower binding affinity to lipopolysaccharide and peptidoglycan. rCgDM9CP-2 also exhibited binding activity towards fungi (Pichia pastoris and Yarrowia lipolytica), gram-positive bacteria (Staphylococcus aureus and Micrococcus luteus), and gram-negative bacteria (Escherichia colt, Vibrio anguillarum, Aeromonas hydrophila and V. splendidus). It could agglutinate fungi P. pastoris and Y. lipolytica, and inhibit the growth of ...