Synthesis, Efficacy, and Molecular Targeting of Hydrazide Class trans-translation Inhibitors

Open Access
Author:
Babunovic, Gregory Hunter
Area of Honors:
Microbiology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Kenneth Charles Keiler, Thesis Supervisor
  • Sarah Ellen Ades, Honors Advisor
  • Scott Brian Selleck, Faculty Reader
Keywords:
  • antibiotics
  • bacteria
  • trans-translation
  • inhibitor
  • protein
  • click chemistry
  • synthesis
  • hydrazide
  • target
  • pathogen
Abstract:
Antibiotic resistance is a serious and growing problem in the modern world, and the discovery and characterization of novel antimicrobials is a top priority. Trans-translation, a conserved and oftentimes essential ribosome-rescue process in bacteria, is a promising target for novel antibacterial drugs. A high-throughput screening assay for the in vivo inhibition of trans-translation identified several molecular classes of compounds that potently inhibit this pathway; members of these classes have shown antibiotic activity against pathogenic and nonpathogenic bacteria. Here, various members of a novel class of trans-translation inhibitors with an acyl hydrazide-thiol-amide substructure were synthesized and tested for antibiotic activity against both pathogenic and nonpathogenic bacteria. An inhibitor with confirmed antibiotic efficacy was used in combination with other known inhibitors of trans-translation and was found to have additive effects with members of the oxadiazole class, implying a related molecular target. A molecular probe for the novel class of inhibitors was synthesized and used in a click chemistry based assay to identify protein binding partners of this class of compounds within bacterial lysates. The click chemistry-based assay identified a protein of approximately 25 kDa that appears to be selectively bound by this probe; this protein is only bound in lysates containing accumulated stalled non-stop ribosomal complexes that are substrates for the trans-translation reaction. Future studies will seek to validate this result and investigate whether this protein is a target of the novel inhibitor class.