Small RNAs ofMycobacterium tuberculosisin Adaptation to Host-Like Stress Conditions in vitro

The regulatory mechanisms of pathogenic bacteria contribute to their survival under stress conditions in the host environment, which allows them to avoid the immune system of the macroorganism. Small, noncoding RNAs were previously found to regulate some metabolic processes ofMycobacterium tuberculosis.We have revealed that the viability ofM. tuberculosisin host-like conditions depends on the expression level of small RNAs. Strains overexpressing small RNA MTS1338 and MTS0997 inM. tuberculosiswere produced, and their survival under stressful conditions in vitro and in infected human macrophages were studied. We found that overexpression of the small, noncoding RNA MTS1338 increased bacterial resistance to the stressful effects of hydrogen peroxide, nitric oxide, an acidic environment, and a long-term lack of nutrients at different growth phases and contributed to the viability of bacteria in infected macrophages. An overexpression of the small, noncoding RNA MTS0997 did not significantly affect cell viability under stress conditions. Thus, the two studied small RNAs play different roles in the mycobacterial adaptation to intracellular stresses during infection.