Molecular cloning, sequence characterization, and expression analysis of C-type lectin (CTL) and ER-Golgi intermediate compartment 53-kDa protein (ERGIC-53) homologs from the freshwater prawn, .

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Lectin protein families are diverse and multi-functional in crustaceans. The carbohydrate-binding domains (CRDs) of lectins recognize the molecular patterns associated with pathogens and orchestrate important roles in crustacean defense. In this study, two lectin homologs, a single CRD containing C-type lectin (CTL) and an L-type lectin (LTL) domain containing endoplasmic reticulum Golgi intermediate compartment 53 kDa protein (ERGIC-53) were identified from the freshwater prawn, . The open reading frames of and were 654 and 1,515 bp, encoding polypeptides of 217 and 504 amino acids, respectively. Further, MrCTL showed a 20-amino acid transmembrane helix region and 10 carbohydrate-binding residues within the CRD. MrERGIC-53 showed a signal peptide region, a type-I transmembrane region, and a coiled-coil region at the C-terminus. Phylogenetic analysis revealed a close relationship between MrCTL and MrLectin and CTL (MnCTL), whereas MrERGIC-53 shared high sequence identity with ERGIC-53 and MBL-1. A homology-based model predicted small carbohydrate-combining sites with a metal-binding site for ligand binding (Ca binding site) in MrCTL and beta-sheets connected by short loops and beta-bends forming a dome-shaped beta-barrel structure representing the LTL domain of MrERGIC-53. Quantitative real-time polymerase chain reaction detected and transcripts in all examined tissues, with particularly high levels observed in hemocytes, hepatopancreas, and mucosal-associated tissues, such as the stomach and intestine. Further, the expression levels of and transcripts were remarkably altered after challenge, suggesting putative function in host innate immunity.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10499-022-00845-3.