A novel C-type lectin with a YPD motif from Portunus trituberculatus (PtCLec1) mediating pathogen recognition and opsonization. (May 2020)

• Record Type: Journal Article
• Authors: Su, Yue; Liu, Yuan; Gao, Fengtao; Cui, Zhaoxia
• Is Part Of: Developmental and comparative immunology. Volume 106(2020)
• Publication Date: 2020-05
• Subjects: Portunus trituberculatus -- C-type lectin -- Pathogen recognition -- Phagocytic activity -- Antimicrobial peptides; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2020.103609
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: C-type lectins are a superfamily of Ca 2+ -dependent carbohydrate-recognition proteins that function as pattern recognition receptors (PRRs) in innate immune system. In this study, a new C-type lectin was identified from the swimming crab Portunus trituberculatus (PtCLec1). The full-length cDNA of PtCLec1 was 873 bp encoding 176 amino acids. The predicted PtCLec1 protein contained a signal peptide and a single carbohydrate-recognition domain with a special YPD motif. The PtCLec1 transcripts were mainly detected in hepatopancreas and its relative expression levels were significantly up-regulated after the challenges of Vibrio alginolyticus, Micrococcus luteus and Pichia pastoris . The recombinant PtCLec1 (rPtCLec1) could bind all the tested pathogen-associated molecular patterns (PAMPs), including lipopolysaccharides (LPS), peptidoglycan (PGN) and glucan (GLU), and microorganisms, including V. alginolyticus, V. parahaemolyticus, Pseudomonas aeruginosa, Staphylococcus aureus, M. luteus and P. pastoris . It also exhibited strong activity to agglutinate bacteria and yeast in a Ca 2+ -dependent manner, and such agglutinating activity could be inhibited by d -galactose and LPS. Moreover, rPtCLec1 revealed antimicrobial activity against the tested Gram-negative ( V. alginolyticus, V. parahaemolyticus and P. aeruginosa ) and Gram-positive bacteria ( S. aureus and M. luteus ), and promoted the clearance of V. alginolyticus in vivo and hemocyte phagocytosis in vitro . Knockdown of PtCLec1 could down-regulate the expression of phagocytosis-related genes, but enhance the expression levels of prophenoloxidase (proPO) system-related genes, mannose-binding lectin (MBL), antimicrobial peptides (AMPs), MyD88 and Relish. All these results indicate that PtCLec1 might act as a PRR in immune recognition and an opsonin in pathogen elimination. Highlights: A novel C-type lectin with a YPD motif (PtCLec1) was isolated from P. trituberculatus. The expression levels of PtCLec1 were significantly up-regulated after bacteria or fungi challenge. PtCLec1 acted as a pattern recognition receptor with antibacterial activity. PtCLec1 promoted hemocyte phagocytosis and bacterial clearance. PtCLec1 might regulate the expression of AMPs, proPO system-related and complement-like genes.