A New Synthetic Peptide Having Two Target of Antibacterial Action in E. coli ML35.

Gabriela Arévalo-Pinzón,Walter H Pérez,Diana Suárez,Adriana Barreto-Santamaría,Manuel E Patarroyo,Hernando Curtidor,Chonny Herrera

doi:10.3389/fmicb.2016.02006

Abstract

The increased resistance of microorganisms to the different antimicrobials available to today has highlighted the need to find new therapeutic agents, including natural and/or synthetic antimicrobial peptides (AMPs). This study has evaluated the antimicrobial activity of synthetic peptide 35409 (RYRRKKKMKKALQYIKLLKE) against Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 15442 and Escherichia coli ML 35 (ATCC 43827). The results have shown that peptide 35409 inhibited the growth of these three bacterial strains, having 16-fold greater activity against E. coli and P. aeruginosa, but requiring less concentration regarding E. coli (22 μM). When analyzing this activity against E. coli compared to time taken, it was found that this peptide inhibited bacterial growth during the first 60 min and reduced CFU/mL 1 log after 120 min had elapsed. This AMP permeabilized the E. coli membrane by interaction with membrane phospholipids, mainly phosphatidylethanolamine, inhibited cell division and induced filamentation, suggesting two different targets of action within a bacterial cell. Cytotoxicity studies revealed that peptide 35409 had low hemolytic activity and was not cytotoxic for two human cell lines. We would thus propose, in the light of these findings, that the peptide 35409 sequence should provide a promising template for designing broad-spectrum AMPs.

Highlights

Antibiotics are molecules combating part of the infections produced by bacteria
Our results suggested that peptide 35409 permeabilized E. coli ML35 membrane through its interaction with phosphatidylethanolamine (PE), thereby enabling peptide molecule entry to a cell where it interacts with the DNA, inhibiting its synthesis and bacterial cell division
The broth dilution method revealed that peptide 35409 had antimicrobial activity against Gram-negative bacteria (MIC 22 μM against E. coli and Minimal inhibitory concentration (MIC) 44 μM against P. aeruginosa) and activity against Gram-positive bacteria (S. aureus) at greater concentration (350 μM), whilst peptides 38659 and 35415 had no effect on bacterial growth at any concentration assayed here (Table 1)

Summary

Introduction

The appearance of resistant strains, such as vancomycin-resistant Staphylococcus aureus, methicillinresistant Staphylococcus epidermidis, ampicillin-resistant and carbapenemase-resistant Escherichia coli, has become a global public health problem and driven the search for new therapeutic compounds having antimicrobial activity which can counteract this phenomenon (RodriguezNoriega et al, 2010; Elhani et al, 2012; Kaase et al, 2016). This has led to discovering and isolating natural antimicrobial peptides (AMPs) and developing synthetic peptides having antimicrobial activity and improved selectivity (Broekaert et al, 1995; Frecer et al, 2004; Chen et al, 2005; Jenssen et al, 2006; Bea Rde et al, 2015). AMP activity and mechanism of action have been related to their amino acid sequence, concentration, net charge, secondary structure, hydrophobicity, as well as the bacterial membrane composition (Dathe et al, 1997; Epand et al, 2005; Spindler et al, 2011)

Methods

Results

Conclusion