Molecular structure, expression and antibacterial characterization of a novel antimicrobial peptide NK-lysin from the large yellow croaker Larimichthys crocea

• Published in: Aquaculture 2019-02, Vol.500, p.315-321
• Main Authors: Zhou, Qi-Jia, Wang, Jun, Mao, Yong, Liu, Min, Su, Yong-Quan, Ke, Qiao-Zhen, Chen, Jia, Zheng, Wei-Qiang
• Format: Article
• Language: English
• Subjects: Antibacterial activity; Antimicrobial peptide; Larimichthys crocea; NK-lysin; Pathogen infection
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2018.10.012

A commercially important marine fish of the Chinese aquaculture industry, the large yellow croaker (Larimichthys crocea), has been seriously threatened by white spot disease and bacterial infection caused by a ciliate protozoan parasite Cryptocaryon irritans. Chemical drugs have a low efficiency in preventing this disease and have side effects on the environment; therefore, new methods for disease treatment are urgently needed. NK-lysin is the component of natural killer cells (NK) and cytotoxic T lymphocytes (CTLs), and is considered a potential antimicrobial peptide. In the current study, we describe LCNKL2 in the large yellow croaker, a novel NK-lysin gene obtained from a liver transcriptome database. The open reading frame of its cDNA sequence was 417 bp, which coded for 138 amino acids. Six completely conserved cysteine residues and a Saposin B domain were found in its deduced amino acid sequence. Compared with NK-lysins reported in other teleosts and higher vertebrates, the polypeptide structure of LCNKL2 is more variable, but still contains the characteristics seen in other NK-lysin members, providing clear evidence it belongs to the NK-lysin family. In healthy large yellow croaker, the LCNKL2 gene was mainly detected in head kidney, spleen and gill, and not detected in brain. During pathogen stimulation, the expression of LCNKL2 gene significantly changed, suggesting a role in the fishes immune response. A short polypeptide from the core region of the LCNKL2 mature peptide sequence was synthesized and its antibacterial activity was tested. The result showed that this short peptide could inhibit Staphylococcus aureus and Vibrio harveyi growth effectively, but was not effective against Aeromonas hydrophila and Photobacteria damselae. Our results indicate LCNKL2 is a novel member of the teleosts NK-lysin family, and as an immune-related factor is involved in the immune response induced by pathogens. •A novel antimicrobial peptide member of the NK-lysin family, LCNKL2, was founded in the large yellow croaker.•The sequence and structure of LCNKL2 gene were described.•Tissues expression profiles and inducible expression profiles of LCNKL2 were investigated.•A short peptide was synthetic and its antibacterial activity was tested.