Antimicrobial function of the GAPDH-related antimicrobial peptide in the skin of skipjack tuna, Katsuwonus pelamis

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• 作者：Jung-Kil Seo ; Min Jeong Lee ; Hye-Jin Go ; Yeon Jun Kim ; Nam Gyu Park
• 关键词：Skipjack tuna skin ; Antimicrobial peptide ; GAPDH ; Innate immunity
• 刊名：Fish & Shellfish Immunology
• 出版年：February, 2014
• 年：2014
• 卷：36
• 期：2
• 页码：571-581
• 全文大小：2052 K

文摘

A 3.4聽kDa of antimicrobial peptide was purified from an acidified skin extract of skipjack tuna, Katsuwonus pelamis, by preparative acid-urea-polyacrylamide gel electrophoresis and C₁₈ reversed-phase HPLC. A comparison of the N-terminal amino acid sequence of the purified peptide with that of other known polypeptides revealed high sequence homology with the YFGAP (Yellowfin tuna Glyceraldehyde-3-phosphate dehydrogenase-related Antimicrobial Peptide); thus, this peptide was identified as the skipjack tuna GAPDH-related antimicrobial peptide (SJGAP). SJGAP showed potent antimicrobial activity against Gram-positive bacteria, such as Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, and Streptococcus iniae (minimal effective concentrations [MECs], 1.2-17.0聽渭g/mL), Gram-negative bacteria, such as Aeromonas hydrophila, Escherichia coli D31, and Vibrio parahaemolyticus (MECs, 3.1-12.0聽渭g/mL), and against Candida albicans (MEC, 16.0聽渭g/mL) without significant hemolytic activity. Antimicrobial activity of this peptide is heat-stable but salt-sensitive. According to the secondary structural prediction and the homology modeling, this peptide consists of three secondary structural motifs, including one 伪-helix and two parallel 尾-strands, and forms an amphipathic structure. This peptide showed neither membrane permeabilization ability nor killing ability, but did display a small degree of leakage ability. These results suggest that SJGAP acts through a bacteriostatic process rather than bactericidal one. SJGAP is another GAPDH-related antimicrobial peptide isolated from skipjack tuna and likely plays an important role for GAPDH in the innate immune defense of tuna fish.