Bacterial toxin-antitoxin modules as drug targets

The genomes of bacteria and archaea contain small operons encoding a "toxin" and its corresponding neutralizing "antitoxin". These gene pairs form a so-called toxin-antitoxin (TA) module of which the physiological function is heavily debated. They are activated during episodes of stress and ectopic overexpression
of the toxin leads irreversibly to cell death. TA modules are present in almost every bacterial species including S. aureus MRSA strains and they are particular ubiquitous in the genomes of a number of opportunistic pathogens such as M. tuberculosis. TA modules can be considered as internal time bombs. Interfering with the interaction between toxin and antitoxin or with the interaction between antitoxin and its operator DNA would detonate the bomb and kill the micro-organism. In this project, I wish to validate the potential of TA modules as targets for the development of novel antibiotics. Using our nanobody technology,
the effects of disrupting antitoxin-DNA and toxin-antitoxin interactions on cellular physiology will be investigated for several families of TA modules under natural expression levels in order to evaluate if this route can lead to cell death or rather induces persisters. Furthermore, in a collaborative effort, the S. aureus mazEF module will be used to screen for compounds that activate the toxin by disrupting toxin-antitoxin interactions. The mechanisms of inhibition of these compounds, which are directed against the MazF toxin, will be studied using a combination of enzymology, biophysics and structural biology.