Synergism of Leu-Lys rich antimicrobial peptides and chloramphenicol against bacterial cells.
To investigate the antibiotic activity and synergistic effect, analogues were designed to increase not only net positive charge by Lys-substitution but also hydrophobic helix region by Leu-substitution from CA (1-8)-MA (1-12) hybrid peptide (CA-MA). In particular, CA-MA analogue P5 (P5), designed by flexible region (GIG-->P)-substitution, Lys- (positions 4, 8, 14, 15) and Leu- (positions 5, 6, 12, 13, 16, 17, 20) substitutions, showed potent antibacterial activity in minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC) without having hemolytic activity. In addition, P5 and chloramphenicol has potent synergistic effect against tested cell lines. As determined by propidium iodide (PI) staining, flow cytometry showed that P5 plus chloramphenicol-treated cells had higher fluorescence intensity than untreated, P5- and chloramphenicol-treated cells. The effect on plasma membrane was examined by investigating the transmembrane potential depolarizing experiments of S. aureus with P5 and chloramphenicol. The result showed that the peptide exerts its antibacterial activity by acting on the plasma membrane. Furthermore, P5 caused significant morphological alterations of S. aureus, as shown by scanning electron microscopy. Our results suggest that peptide P5 is an excellent candidate as a lead compound for the development of novel anti-infective agents and synergistic effects with conventional antibiotic agents but lack hemolytic activity.
Park
Yoonkyung
Y
Research Center for Proteineous Materials, Chosun University, 375 Seosuk-Dong, Dong-Ku, Kwangju 501-759, Korea.
Park
Soon Nang
SN
Park
Seong-Cheol
SC
Shin
Sun Oh
SO
Kim
Jin-Young
JY
Kang
Sung-Jin
SJ
Kim
Mi-Hyun
MH
Jeong
Chan-Young
CY
Hahm
Kyung-Soo
KS
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000138:chemical synthesis / Q000737:chemistry; D023181:Antimicrobial Cationic Peptides / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000737:chemistry; D001419:Bacteria / Q000187:drug effects*; D002463:Cell Membrane Permeability / Q000187:drug effects; D002701:Chloramphenicol / Q000008:administration & dosage*; D015195:Drug Design; D004357:Drug Synergism; D004912:Erythrocytes / Q000187:drug effects / Q000648:ultrastructure; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D013211:Staphylococcus aureus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D002701:Chloramphenicol