title: Mechanism of action of the tri-hybrid antimicrobial peptide  LHP7 from lactoferricin, HP and plectasin  on Staphylococcus aureus.
abstract: The tri-hybrid peptide-LHP7 has the potent activity against Gram-positive and Gram-negative as well as fungi, but its mechanism of action has remained elusive. The effluences of LHP7 on the Staphylococcus aureus cell membrane and targets of intracellular action were investigated. LHP7 exhibited an inhibitory effect on the S. aureus growth, similar to those achieved by plectasin, vancomycin and gramicidin. The membrane integrity studies confirmed that LHP7 disrupted the cell membrane, indicating a membrane permeabilizing killing action. A marginal decline in the intensity fluorescence indicated no significant depolarization of the membrane potential following LHP7 treatment. Furthermore, electron microscopy showed that cell shrinkage, cell wall thickening, cellular content leakage, and cell disruption were observed in the cells treated with LHP7. A gel retardation assay showed that LHP7 bound to the genomic DNA of S. aureus or plasmid DNA at a mass ratio of 2.5–10 (peptide/DNA). Circular dichroism indicated that LHP7 inserted into the groove of DNA. The cell cycle analysis showed that after the treatment with LHP7 for 30 and 60 min, the proportion of cells in I-phase increased from 8.71 to 12.09 % and from 8.71 to 15.68 %, indicating that LHP7 induced arrest of cells in the I-phase. These results would conduce to elucidate its underlying antibacterial mechanism.
authors.forename: Di
authors.initials: D
authors.lastname: Xi
authors.forename: Xiumin
authors.initials: X
authors.lastname: Wang
authors.forename: Da
authors.initials: D
authors.lastname: Teng
authors.forename: Ruoyu
authors.initials: R
authors.lastname: Mao
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D004269:DNA, Bacterial / Q000187:drug effects; D007781:Lactoferrin / Q000737:chemistry* / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D008854:Microscopy, Electron; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D023181:Antimicrobial Cationic Peptides; D004269:DNA, Bacterial; D010455:Peptides; D011993:Recombinant Fusion Proteins; C504857:plectasin; C082171:lactoferricin B; D007781:Lactoferrin