title: Antimicrobial function of the GAPDH-related antimicrobial peptide in the skin of skipjack tuna, Katsuwonus pelamis.
abstract: A 3.4 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 μg/mL), Gram-negative bacteria, such as Aeromonas hydrophila, Escherichia coli D31, and Vibrio parahaemolyticus (MECs, 3.1-12.0 μg/mL), and against Candida albicans (MEC, 16.0 μg/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 α-helix and two parallel β-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.
authors.affiliation: Department of Food Science and Biotechnology, Kunsan National University, Kunsan 573-701, Republic of Korea.
authors.forename: Jung-Kil
authors.initials: JK
authors.lastname: Seo
authors.affiliation: Department of Biotechnology, Pukyong National University, Busan 608-737, Republic of Korea.
authors.forename: Min Jeong
authors.initials: MJ
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Pukyong National University, Busan 608-737, Republic of Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Go
authors.affiliation: West Vancouver Secondary School, 1750 Mathers Ave., West Vancouver, BC V7V 2G7, Canada.
authors.forename: Yeon Jun
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, Pukyong National University, Busan 608-737, Republic of Korea. Electronic address: ngpark@pknu.ac.kr.
authors.forename: Nam Gyu
authors.initials: NG
authors.lastname: Park
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000378:metabolism*; D001419:Bacteria / Q000276:immunology; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000737:chemistry / Q000378:metabolism*; D017433:Protein Structure, Secondary; D016415:Sequence Alignment / Q000662:veterinary; D012867:Skin / Q000276:immunology; D014413:Tuna / Q000276:immunology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases
keywords: Antimicrobial peptide; GAPDH; Innate immunity; Skipjack tuna skin