Characterization and expression analysis of a goose-type lysozyme from the rock bream Oplegnathus fasciatus, and antimicrobial activity of its recombinant protein

摘要: Lysozyme (muramidase) represents an important defense molecule of the fish innate immune system. Known for its bactericidal properties, lysozyme catalyzes hydrolysis β-(1,4)-glycosidic bonds between N-acetyl glucosamine and muramic acid in peptidoglycan layer bacterial cell walls. In this study, complete coding sequence a g-type (RBgLyz) was identified Oplegnathus fasciatus rock bream genome by means multi-tissue normalized cDNA pyrosequencing using Roche 454 GS-FLX™ technology. RBgLyz is composed 669 bp, with 567 bp open reading frame that encodes 188 amino acids. Protein motif searches indicated contains soluble lytic transglycosylase domain involved maintaining wall integrity. Furthermore, shares significant identity (81.4%) Chinese perch Siniperca chuatsi. Quantitative real-time RT-PCR analysis results showed transcripts are constitutively expressed various tissues from healthy breams. order to determine function immunity, expression analyzed head kidney following exposure known stimulants or pathogens. were significantly up-regulated response challenge lipopolysaccharide (LPS) Edwardsiella tarda, as compared non-injected control fish. Polyinosinic:polycytidylic (poly I:C) dsRNA stimulated moderate RBgLyz, did Streptococcus iniae but lesser extent. There no specific time-dependent effects on mRNA observed iridovirus (RBIV) infection. Taken together, gene plays role LPS, poly I:C, E. tarda S. bream. Thus, we generated recombinant Escherichia coli system characterized antimicrobial activity. Our had activity against Gram-negative Vibrio salmonicida, Gram-positive Listeria monocytogenes, Micrococcus lysodeikticus. addition, observations scanning electron microscope (SEM) confirmed morphology M. lysodeikticus altered presence RBgLyz.