A GAPDH-related novel antimicrobial peptide from the skin of yel

Purification and characterization of YFGAP, a GAPDH-related novel antimicrobial peptide, from the skin of yellowfin tuna, Thunnus albacares
Jung-Kil Seo, Min Jeong Lee, Hye-Jin Go, Tae Hyun Park, Nam Gyu Park, Fish Shellfish Immunol., 2012, 33, 743–752.
http://dx.doi.org/10.1016/j.fsi.2012.06.023
Copyright © 2012 Elsevier Ltd. All rights reserved.

A 3.4 kDa of antimicrobial peptide was purified from an acidified skin extract of the yellowfin tuna, Thunnus albacares, 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 homology with the N-terminus of glyceraldehyde-3-phosphate dehydrogenase (GAPDH); thus, this peptide was designated as the yellowfin tuna GAPDH-related antimicrobial peptide (YFGAP). YFGAP showed potent antimicrobial activity against Gram-positive bacteria, such as Bacillus subtilis, Micrococcus luteus, and Streptococcus iniae (minimal effective concentrations [MECs], 1.2–17.0 μg/mL), and Gram-negative bacteria, such as Aeromonas hydrophila, Escherichia coli D31, and Vibrio parahaemolyticus (MECs, 3.1–12.0 μg/mL) without significant hemolytic activity. According to the secondary structural prediction and the homology modeling, this peptide forms an amphipathic structure and consists of three secondary structural motifs including one α-helix and two parallel β-strands. This peptide did not show membrane permeabilization ability and its activity was bacteriostatic rather than bactericidal. This is the first report of the isolation of an antimicrobial peptide from a tuna species and the first description of the antimicrobial function of the N-terminus of GAPDH of an animal species.