The serum of rabbitfish (Siganus oramin) has antimicrobial activity to some pathogenic organisms and a novel serum l-amino acid oxidase is isolated

L-Amino Acid Oxidase, a Novel Antibacterial Protein in the Rockfish <i>Sebastes schlegeli</i>

“…The result revealed the high homology of serum LAO I-A with LAO family proteins derived from fish. The determined 140 amino acid residues of serum LAO I-A were closely similar to SSAP; the identity of the amino acid sequence was 98% with SSAP, followed by 75%, 68%, 66% and 64%, respectively, with AIP from mackerel viscera, MPLAO3 from great sculpin skin mucus, psLAAO1 from flounder gill secretion and SR-LAAO from rabbitfish serum (Jung et al 2000;Nagashima et al 2009;Kasai et al 2010;Wang et al 2011), suggesting a novel LAO in serum of the rockfish.…”

“…piscicida bodies and pores into V. parahaemolyticus cells, strongly supporting antibacterial kinetics of SSAP. Wang et al (2011) reported that SR-LAAO from the serum of rabbitfish Siganus oramin also showed different morphological changes in bacteria by SEM observation. When S. aureus was treated with the rabbitfish serum, the surface of the S. aureus was wrinkled, the cell membranes deformed, causing the formation of blebs on the cell surface.…”

“…Kasai et al (2010) reported that an antibacterial LAO (ps-LAAO) isolated from epidermis mucus of the flounder P. stellatus's gills was predominantly localized in the undifferentiated cells surrounding the vacuolated mucus-secreting cells of the gills, within the epithelia of the primary and secondary lamella. Furthermore, the rabbitfish S. oramin serum LAO (SR-LAAO) with antibacterial and antiparasitic activities was detected not only in blood but also the spleen, kidney and gills (Wang et al 2011). It is noteworthy that localization of LAOs in fish varies among fish species, suggesting distinct functions of LAOs among fish species.…”

“…LAO with a potent antibacterial activity was first isolated from skin mucus of rockfish (Kitani et al 2007a). Thereafter, fish LAOs were isolated not only from skin mucus of great sculpin Myoxocephalus polyacanthocephalus (Nagashima et al 2009) and starry flounder Platichthys stellatus (Kasai et al 2010), but also from serum of rockfish (Kitani et al 2010) and white-spotted rabbitfish Siganus oramin (Wang et al 2011). High-throughput sequencing technologies enabled LAO gene mining from the genome database and the transcriptome analysis.…”

“…Furthermore, it should be noted that the serum had at least four LAO isoenzymes in the purification procedure, while the skin mucus had only SSAP. The serum LAO might be of great advantage to the innate defense system, thereby the serum LAO could be active even LAAO, was demonstrated to localize in the spleen, kidney, gill and blood by immunohistochemical analysis (Wang et al 2011). In mammals, interleukin-4-induced gene-1 (Il4I1, formerly Fig1) initially identified in mouse B lymphocytes was found to be a novel LAO family protein and indeed acted as an antibiotic against Gram-negative and Gram-positive bacteria (Chu and Paul 1997;Manson et al 2004;Puiffe et al 2013).…”