Benzoic Acid-Inducible Gene Expression in Mycobacteria

Conditional expression is a powerful tool to investigate the role of bacterial genes. Here, we adapt the Pseudomonas putida -derived positively regulated XylS/ Pm expression system to control inducible gene expression in Mycobacterium smegmatis and Mycobacterium tuberculosis , the causative agent of human tuberculosis. By making simple changes to a Gram-negative broad-host-range XylS/ Pm- regulated gene expression vector, we prove that it is possible to adapt this well-studied expression system to non-Gram-negative species. With the benzoic acid-derived inducer m -toluate, we achieve a robust, time- and dose-dependent reversible induction of Pm -mediated expression in mycobacteria, with low background expression levels. XylS/ Pm is thus an important addition to existing mycobacterial expression tools, especially when low basal expression is of particular importance.