title: A peptide derived from phage display library exhibits antibacterial activity against E. coli and Pseudomonas aeruginosa.
abstract: Emergence of drug resistant strains to currently available antibiotics has resulted in the quest for novel antimicrobial agents. Antimicrobial peptides (AMPs) are receiving attention as alternatives to antibiotics. In this study, we used phage-display random peptide library to identify peptides binding to the cell surface of E. coli. The peptide with sequence RLLFRKIRRLKR (EC5) bound to the cell surface of E. coli and exhibited certain features common to AMPs and was rich in Arginine and Lysine residues. Antimicrobial activity of the peptide was tested in vitro by growth inhibition assays and the bacterial membrane permeabilization assay. The peptide was highly active against gram-negative organisms and showed significant bactericidal activity against E. coli and P. aeruginosa resulting in a reduction of 5 log(10) CFU/ml. In homologous plasma and platelets, incubation of EC5 with the bacteria resulted in significant reduction of E. coli and P. aeruginosa, compared to the peptide-free controls. The peptide was non-hemolytic and non-cytotoxic when tested on eukaryotic cells in culture. EC5 was able to permeabilize the outer membrane of E. coli and P. aeruginosa causing rapid depolarization of cytoplasmic membrane resulting in killing of the cells at 5 minutes of exposure. The secondary structure of the peptide showed a α-helical conformation in the presence of aqueous environment. The bacterial lipid interaction with the peptide was also investigated using Molecular Dynamic Simulations. Thus this study demonstrates that peptides identified to bind to bacterial cell surface through phage-display screening may additionally aid in identifying and developing novel antimicrobial peptides.
authors: Section of Cell Biology, Laboratory of Cellular Hematology, Division of Hematology, Center for Biologics Evaluation and Research, US Food and Drug Administration, Bethesda, Maryland, United States of America.
authors: Shilpakala
authors: S
authors: Sainath Rao
authors: Ketha V K
authors: KV
authors: Mohan
authors: Chintamani D
authors: CD
authors: Atreya
mesh_terms: D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors; D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D001792:Blood Platelets / Q000382:microbiology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002463:Cell Membrane Permeability; D004285:Dogs; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects; D061985:Madin Darby Canine Kidney Cells; D008564:Membrane Potentials / Q000187:drug effects; D056004:Molecular Dynamics Simulation; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D019151:Peptide Library; D010949:Plasma / Q000382:microbiology; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D009842:Oligopeptides; D019151:Peptide Library; D000255:Adenosine Triphosphate