Biophysical characterization of the intracellular localization and cellular transport of inhibitor/antimicrobial peptides

Antibiotic resistance, resulting from the misuse and underuse of antimicrobial drugs, has been realized right after the discovery of penicillin. One of the most important reasons for resistance against the commonly used beta-lactam antibiotics is the bacterial synthesis of the beta-lactamase enzyme that hydrolyzes the antibiotic. In the fight against resistant bacteria, beta-lactamase inhibitors are usually administered along with this class of antibiotics. Unfortunately mutations of the beta-lactamase enzyme has led to resistance against available inhibitors. As a result, inhibitor design is an important issue in the field of antibiotic resistance. Due to their high efficacy and low toxicity, peptide based inhibitors constitute an attractive alternative to small organic molecule drugs. However, their larger size and hydrophobicity restrict their uptake. Along with the discovery of cell penetrating peptides (CPP), the search for peptide based drugs has regained attention and peptide drugs that target intracellular proteins have been designed. Furthermore, it is well established that antimicrobial peptides that are based on bee or snake venom disrupt cell wall and cause cell death. These findings have shown that the use of antimicrobial peptides is an effective strategy in the fight against antibiotic resistance.

In our previous projects we have proposed a novel peptide as a potential beta-lactamase inhibitor. The detailed understanding of the extent to which the peptide affects bacterial cells will enable the development of similar peptide inhibitors. The aim of this project is to experimentally and computationally study the effect of this peptide and similar peptides, which will be designed based on the strategy used in designing the novel inhibitor peptide, by determining the minimum inhibitory concentration (antibiotic susceptibility), measuring bacterial selectivity (mammalian cell toxicity experiments) monitoring the effect on bacterial cells (SEM and Fluorescence microscopy) and analyzing the mechanism of action (molecular dynamic simulations) on cellular and atomic levels.

Our long term objective is to design effective beta-lactam inhibitor peptides that can be transported across the cell wall. Expanding the knowledge base of antimicrobial peptide action will accelerate and advance antimicrobial drug discovery studies.