Small Molecule Inhibitors of the trans-translation Pathway Have Antibiotic Activity Against Mycobacterium smegmatis
Open Access
- Author:
- Chambers, Benjamin Stewart
- Area of Honors:
- Microbiology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Kenneth Charles Keiler, Thesis Supervisor
Dr. Sarah Ellen Ades, Thesis Honors Advisor
Dr. Wendy Hanna-Rose, Faculty Reader - Keywords:
- smegmatis
tuberculosis
tb
small molecule inhibitors
trans-translation
tmRNA
antibiotic
drug
chambers - Abstract:
- Antibiotic resistance has been spreading at an alarming rate over the past few decades. Tuberculosis (TB), the most prevalent infectious disease in the world, is becoming even tougher to treat now that many of the drugs used to fight it are becoming more and more ineffective. It is necessary to begin developing new antimicrobial compounds that target novel pathways in bacteria so that TB can be better treated in the future. One such novel pathway is the trans-translation pathway which is responsible for rescuing stalled ribosomes. It is required for growth and virulence in many pathogenic bacteria but is not found in eukaryotic cells. This provides selective toxicity and a favorable approach to fighting pathogens. In an attempt to find new drugs to treat TB, this study used Mycobacterium smegmatis as a model for Mycobacterium tuberculosis, the bacterium that causes TB, because M. smegmatis is non-pathogenic and grows quickly making it much easier to work with. Small molecules previously shown to inhibit the trans-translation pathway in E. coli were tested in M. smegmatis using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays to determine how effective each one is at preventing growth of the bacteria. After the best inhibitors (A7, D3, D7, E2, and E5) were identified, UV mutagenesis and fluorescence assays were used to search for the target and mechanism of action for each inhibitor. The fluorescence assays using mCherry-expressing strains of M. smegmatis suggested that inhibitor E5 is likely inhibiting the proteolysis step of the trans-translation pathway while inhibitors A7 and D7 are inhibiting a step before proteolysis. Future work will concentrate on improving the fluorescence assays and running binding assays with possible target proteins to continue the search for the specific targets of each of the best inhibitors.