Defensing role of novel piscidins from largemouth bass (Micropterus salmoides) with evidence of bactericidal activities and inducible expressional delineation

• Published in: Microbiological research Vol. 256; p. 126953
• Main Authors: Duan, Yuxin, Ouyang, Jianhong, Mo, Guoxiang, Hao, Weijing, Zhang, Peng, Yang, Huaixin, Liu, Xiaowei, Wang, Runying, Cao, Biyin, Wang, Yipeng, Yu, Haining
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 01-03-2022
• Subjects: Animals; Antibiofilm activity; Antimicrobial peptides (AMPs); Antimicrobial Peptides - immunology; Bass - immunology; Bass - microbiology; Fish Proteins - immunology; Fresh Water; Immunity, Innate; Innate immunity; Micropterus salmoides; Piscidin; Antimicrobial peptides (AMPs); Micropterus salmoides; Innate immunity; Antibiofilm activity; Piscidin
• ISSN: 0944-5013; 1618-0623
• DOI: 10.1016/j.micres.2021.126953

•Three novel piscidins (MSPiscidin-1−3) were firstly identified from the largemouth bass, Micropterus salmoides.•MSPiscidin-2 and -3 exhibited potent, broad-spectrum, and rapid antimicrobial activities against aquatic bacteria.•MSPiscidin-2 and -3 kill bacteria by inducing membrane permeabilization and interacting with genomic DNA.•MSPiscidin-2 and -3 could inhibit the formation of bacterial biofilms and eliminate the preformed biofilms.•The three piscidins demonstrated inducible expression pattern upon bacterial infection in multiple organs/tissues of fish.
Micropterus salmoides is an economical important species of freshwater-cultured fish, the in-depth knowledge of its immune system is in urgent development to cope with serious infectious diseases. Piscidin is an important antimicrobial peptide (AMP) family existing in almost all teleosts. However, no piscidin has been reported in largemouth bass. In this study, three novel piscidins (MSPiscidin-1, -2, and -3) were firstly identified and characterized from the largemouth bass. The predicted mature peptides of MSPiscidin-1, -2, and -3 (consists of 24, 27, 25 amino acid residues, respectively) all adopted an amphipathic α-helical conformation representative of cationic AMPs that are important for membrane permeabilization and antibacterial activity. MSPiscidin-2 and -3 indeed displayed strong, broad-spectrum, and highly efficient antimicrobial activities in vitro against aquatic pathogens, but MSPiscidin-1 didn’t show direct antimicrobial activity. MSPiscidin-2 and -3 killed bacteria mainly by inducing membrane permeabilization, in addition, they also can interact with bacterial genomic DNA, which might influence the DNA replication and transcription. Besides, MSPiscidin-2 and -3 could effectively inhibit the formation of the bacterial biofilm and eliminate the preformed biofilms. In vivo, MSPiscidin-1−3 genes showed an inducible expression pattern in the tested tissues upon Vibrio harveyi infection, which further indicated the key roles of piscidins in innate immunity in largemouth bass. Overall, this study will supplement the understanding of M. salmoides innate immune system and provide candidates for the design of novel peptide antibacterial agents used in aquaculture.