Poster abstracts

Poster number 7 submitted by Teresa Wolak

A Systematic Approach to Ribosome-Targeting using the Antimicrobial Peptide Oncocin

Teresa Wolak (Department of Chemistry, Wayne State University), Rabiul Islam (Department of Chemistry, Wayne State University), Hien M. Nguyen (Department of Chemistry, Wayne State University), Christine S. Chow (Department of Chemistry, Wayne State University)

Abstract:
The continuous identification of drug-resistant bacterial species has not been abated by the development of new antibiotics that are effective against resistance mechanisms. Proline-rich antimicrobial peptides (PrAMPs) are an intriguing class for development due to their mutational tolerance and multi-modal mechanism of action. The PrAMP oncocin binds to the bacterial ribosome preventing the accommodation of A-tRNA, inhibiting elongation, and blocking the peptide exit tunnel. In our approach to develop enhanced oncocin derivatives, we deconstructed the development workflow by systematically addressing effects on cellular uptake, rRNA targeting and used a combinational approach to antibiotic evaluation. A multiple sequence alignment (MSA) on the 23S rRNA subunit was conducted to obtain nucleotide conservation in over 1,000 bacterial species, providing a guided approach to 23S ribosome-targeting antibiotics. Employing a cell-based plasmid expression system, we evaluated the antibacterial effects of truncated and/or disubstituted oncocin variants in Escherichia coli. The combinational evaluation of antibacterial activity using minimum inhibitory concentration (MIC) assay verified our cell-based plasmid expression system and led to the identification of an oncocin variant that exhibited a two-fold decrease in MIC compared to oncocin. Molecular-level interactions with the oncocin variant were simulated using molecular docking and modeling to visualize interactions at various stages of translation. The mechanistic flexibility and modularity of PrAMPs enable a tailored approach to target universally conserved ribosomal regions in a wide range of bacterial species.

Keywords: ribosome-targeting antibiotics, proline-rich antimicrobial peptides