Tuberculosis remains one of the leading causes of death from a single pathogen globally.
It is estimated that 1/4 of the world’s population harbors latent tuberculosis, but only a
5–10% of patients will develop active disease. During latent infection, Mycobacterium
tuberculosis can persist unaffected by drugs for years in a non-replicating state with
low metabolic activity. The rate of the successful tuberculosis treatment is curbed by
the presence of these non-replicating bacilli that can resuscitate after decades and also
by the spread of M. tuberculosis drug-resistant strains. International agencies, including
the World Health Organization, urge the international community to combat this global
health emergency. The thienopyrimidine TP053 is a promising new antitubercular lead
compound highly active against both replicating and non-replicating M. tuberculosis
cells, with an in vitro MIC of 0.125 mg/ml. TP053 is a prodrug activated by the reduced
form of the mycothiol-dependent reductase Mrx2, encoded by Rv2466c gene. After
its activation, TP053 releases nitric oxide and a highly reactive metabolite, explaining its
activity also against M. tuberculosis non-replicating cells. In this work, a new mechanism
of TP053 resistance was discovered. M. tuberculosis spontaneous mutants resistant to
TP053 were isolated harboring the mutation L240V in Rv0579, a protein with unknown
function, but without mutation in Rv2466c gene. Recombineering method demonstrated
that this mutation is linked to TP053 resistance. To better characterize Rv0579, the
protein was recombinantly produced in Escherichia coli and a direct interaction between
the Mrx2 activated TP053 and Rv0579 was shown by an innovative target-fishing
experiment based on click chemistry. Thanks to achieved results, a possible contribution
of Rv0579 in M. tuberculosis RNA metabolism was hypothesized, linked to toxin antitoxin
system. Overall, these data confirm the role of Rv0579 in TP053 resistance and
consequently in the metabolism of this prodrug
