PMC

Determination of lactate dehydrogenase (LDH) release from HeLa cell infected with S. Typhimurium and V. vulnificus in the presence or absence condition of actinonin. HeLa cells were infected by S. Typhimurium (A) or V. vulnificus (B) at MOI 20, and supplemented with DMSO or actinonin (15 μM). Then, LDH release from the cells was determined after infection. All values are mean ± standard deviation of three repeated processes. A star and double stars express significant p values (*p < 0.05; **p < 0.01)

Alignment of the homologous PDF domains of various bacteria. The catalytic domains of PDF that are essential to def encoded peptide deformylase for protein synthesis in five foodborne pathogens from this study and other actinonin-sensitive/resistant strains from previous studies were identified [, , ]. I, II and III are the motifs that comprise the catalytic domain. + and − indicate whether the growth of bacteria was inhibited by actinonin or not (+ inhibited, − not inhibited). Grey highlights mean the amino acid residue is not exactly the same but, it still retains amino acid specific functions

Effect of actinonin on swarming motility of S. Typhimurium and V. vulnificus. The inhibition of swarming motility of S. Typhimurium and V. vulnificus was determined by measuring the diameter of swarming zones on actinonin-treated semi-solid agar plates (0.5% agar) containing different concentrations of actinonin (0, 0.05, 0.1, 0.5, 2, 5 μM). An aliquot of 5 μl of S. Typhimurium or V. vulnificus was inoculated onto each plate and the diameter was measured after 20 h incubation at 37 °C for S. Typhimurium and 30 °C for V. vulnificus. (A) Halo images of swarming plates containing different concentrations of actinonin were taken. (B) Diameters of swarming migrations of S. Typhimurium and V. vulnificus were measured. All values are mean ± standard deviation of three repeated processes, and double stars express significant p values (**p < 0.01)

The growth inhibition of actinonin against E. coli O157:H7, L. monocytogenes, S. Typhimurium, S. aureus and V. vulnificus. (A) Chemical structure of actinonin; Actinonin (C₁₉H₃₅N₃O₅) is a pseudo-tripeptide hydroxamate inhibitor derived from l-prolinol and its n-pentyl side chain binds hydrophobic subsite of peptide deformylase (PDF), which inhibits the activity of PDF that removes N-formyl groups before the action of methionine aminopeptidase (MAP) in N-terminal methionine excision (NME) pathway from eubacteria. (B)–(F) five foodborne pathogens were incubated overnight and subcultured in 20 ml of LB broth media until absorbance (O.D.₆₀₀) reached 0.8. Then, growth of the control group and the experimental group with 90 μM actinonin was assessed by measuring the absorbance (O.D.₆₀₀) every 2 h for 8 h post actinonin treatment. All values are mean ± standard deviation of three repeated processes, and double stars express significant p values (**p < 0.01)