Lipopolysaccharide- and β-1,3-glucan-binding protein from Fenneropenaeus merguiensis functions as a pattern recognition receptor with a broad specificity for diverse pathogens in the defense against microorganisms

In crustaceans, lipopolysaccharide- and β-1,3-glucan-binding protein (LGBP) plays an important role in innate immunity by mediating the recognition of pathogens to host cells. Hereby, LGBP was cloned from Fenneropenaeus merguiensis hepatopancreas. Its full-length cDNA (1280 bp) had an open reading frame of 1101 bp, encoding a peptide of 366 amino acids. The LGBP primary structure comprises a recognition motif for β-1,3-linkage of polysaccharides, two integrin binding motifs, a kinase C phosphorylation site and a bacterial glucanase motif. The LGBP mRNA was strongly expressed in hepatopancreas and significantly up-regulated to get the maximum at 12 h upon Vibrio harveyi challenge. Recombinant LGBP (rLGBP) could agglutinate Gram-negative and Gram-positive bacteria including yeast with Ca2+-dependence. V. harveyi agglutination induced by rLGBP was intensively inhibited by lipoteichoic acid, less in order were lipopolysaccharide, β-1,3-glucan and N-acetyl neuraminic acid. Western blotting revealed that rLGBP bound widely to Gram-negative and Gram-positive bacteria and also yeast. By ELISA quantification, rLGBP could bind to β-1,3-glucan better than to lipopolysaccharide and lipoteichoic acid. These findings suggest that LGBP may function as a receptor which recognizes invading diverse pathogens and contribute in F. merguiensis immune response.