Study of the role of cell wall biosynthesis genes in the mechanism of action of avermectins in mycobacteria (Trabajo Fin de Grado, TFG)
The emergence of Mycobacterium tuberculosis strains resistant to the first line conventional treatment generate the necessity to develop new antimicrobial compounds for the disease treatment. A strategy to reduce cost and time can come from drug repurposing as in the case of selamectin. However, its mechanism of action must be first elucidated, using Mycobacterium smegmatis as model organism. In a previous study from the laboratory, it was identified the synergic combination between selamectin and ethambutol by checkerboard.
In this project, it has been observed the absence of interaction with other cell wall synthesis inhibitors as PBTZ-169, what suggests that there is a relationship between the targets of ethambutol and the mechanism of action of selamectin, which has been studied in depth. Overexpression in plasmid and knock out by recombineering mutants of these targets have been built and the first steps to conduct an analysis of transcriptional response of some cell wall biosynthesis genes after treatment with both drugs have been performed..
Compound activity against a bigger inoculum than the standardized have also been characterised, by minimum inhibitory and bactericidal concentrations and time-kill assays, establishing the compound action profile, inoculum dependence and optimal conditions for RNA extraction.
However, the Covid-19’s pandemic has not allowed us to finish these lines of action which require further susceptibility studies to the built mutants and the characterization of the transcriptional response to selamectin and ethambutol’s treatment in the optimal established conditions.