A short peptidoglycan recognition protein protects Boleophthalmus pectinirostris against bacterial infection via inhibiting bacterial activity

Peptidoglycan recognition proteins (PGRPs) belong to a member of pattern-recognition receptors (PRRs), which proposed as antibacterial protein . The present study investigated the antibacterial effect of BpPGRP5 in great blue-spotted mudskipper ( Boleophthalmus pectinirostris ). BpPGRP5 transcript was detected in all tested tissues with the highest expression level in spleen , and its expression was significantly upregulated in spleen, intestine, and kidney following Aeromonas veronii infection. rBpPGRP5 was found to interact with several polysaccharides and bacteria, including Gram-negative bacteria ( Escherichia coli and A. veronii ) and Gram-positive bacteria ( Listeria monocytogenes and Staphylococcus aureus ). rBpPGRP5 inhibited the proliferation of E. coli , S. aureus , L. monocytogenes , and A. veronii in a Zn 2+ -dependent manner. Furthermore, in vivo studies revealed that intraperitoneal injection of rBpPGRP5 improved the survival rate of A. veronii -infected B. pectinirostris , accompanied by decreased bacterial load in the blood, kidney, intestine, and spleen. Taken together, our results indicated that BpPGRP5 is an antimicrobial protein that protects B. pectinirostris against bacterial infection.