Functional whole genome screen of nutrient-starvedMycobacterium tuberculosisidentifies genes involved in antibiotic tolerance

Abstract

Mycobacterium tuberculosis(Mtb), the causative agent of tuberculosis (TB), poses a global health challenge and is responsible for over a million deaths each year. Current treatment regimens are lengthy and complex, and new, abbreviated therapeutic regimens are urgently needed.Mtbadapts to nutrient starvation, a condition experienced during host infection, by shifting its metabolism and becoming tolerant to the killing activity of bactericidal antibiotics. An improved understanding of the mechanisms mediating antibiotic tolerance inMtbcan provide insights into more effective therapeutic strategies. We performed a forward genetic screen to identify candidateMtbgenes involved in tolerance to the two key first-line antibiotics, rifampin and isoniazid, under nutrient-rich and nutrient-starved conditions. In nutrient-rich conditions, we found 220 mutants with differential antibiotic susceptibility (218 in the rifampin screen and 2 in the isoniazid screen). FollowingMtbadaptation to nutrient starvation, 82 mutants showed differential antibiotic susceptibility (80 in the rifampin screen and 2 in the isoniazid screen). Using targeted mutagenesis, we validated the rifampin-hypersusceptible phenotype under nutrient starvation inMtbmutants lacking the following genes:ercc3, moeA1, rv0049,andrv2179c. These findings shed light on potential therapeutic targets, which could help shorten the duration and complexity of antitubercular regimens.