C-type lectin with a QPN motif from swimming crab Portunus trituberculatus displays broad nonself-recognition ability and functions as an opsonin

• Published in: Developmental and comparative immunology 2021-07, Vol.120, p.104066-104066, Article 104066
• Main Authors: Kang, Ting, Xia, Yanting, Dong, Taiwei, Zheng, Xiaoyuan, Yang, Shun, Qian, Shichao, Huang, Mengmeng, Fei, Hui
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs - genetics; Amino Acid Motifs - immunology; Animals; Arthropod Proteins - genetics; Arthropod Proteins - metabolism; Brachyura - genetics; Brachyura - immunology; Brachyura - metabolism; C-type lectin; Carbohydrates; Comparative analysis; Encapsulation; Hemocytes; Hemocytes - metabolism; Immune clearance; Immune response; Immune system; Immunity, Innate; Innate immunity; Lectins; Lectins, C-Type - genetics; Lectins, C-Type - metabolism; Nonself-recognition; Opsonin Proteins - genetics; Opsonin Proteins - metabolism; Pattern recognition; Pattern recognition receptors; Phagocytosis; Phylogeny; Portunus trituberculatus; Receptor mechanisms; Scavenging; Sequence Alignment; Signal Transduction - immunology; Swimming
• ISSN: 0145-305X; 1879-0089
• DOI: 10.1016/j.dci.2021.104066

In the immune system, C-type lectins, as pattern recognition receptors, have an important function. Carbohydrate-recognition domains (CRDs) endow C-type lectins with the function of recognizing and scavenging non-self factors. In the present study, a new C-type lectin (designated as PtCTL-9 according to the order of discovery) from swimming crab (Portunus trituberculatus) was characterized. QPN (Gln-Pro-Asn) and FHS (Phe-His-Ser) were identified as the key motifs that determine carbohydrate binding. Motif QPN was mutated to QPD (Gln-Pro-Asp) (M1) and EPN (Glu-Pro-Asn) (M2) to study its immune function and for comparative analysis. The results showed that PtCTL-9 displayed broad non-self immunity. PtCTL-9 could also function as an opsonin to promote phagocytosis and the in vitro encapsulation of hemocytes. These results indicated that PtCTL-9 has an extensive nonself-recognition ability, regulates pathogen clearance, and its QPN motif is important in PtCTL-9's immune function. •A C-type lectin PtCTL-9 with a novel QPN motif was identified from Portunus trituberculatus.•PtCTL-9 possessed strong binding activity to nonself particles while its two mutants displayed weak binding activity.•PtCTL-9 inhibited the growth of S. cerevisiae.•PtCTL-9 promoted phagocytosis and encapsulation activity of hemocytes in vitro.