Involvement of Mycobacterium smegmatis small noncoding RNA B11 in triacylglycerol accumulation and altered cell wall permeability.

Background: Pathways involving triacylglycerol (TAG) accumulation are thought to play a crucial regulatory role in bacterial growth and metabolism. Despite this understanding, little is known about the biological functions and regulatory mechanisms of small RNAs in Mycobacterium. Mycobacterium smegmatis (M. smegmatis), a type of Mycobacterium, serves as a model organism to investigate the molecular, physiological, and drug resistance features of M. tuberculosis.

Results: In this study, we demonstrated that overexpression of B11 significantly affects bacterial growth and colony morphology, increases antibiotic sensitivity and sodium dodecyl sulfate (SDS) surface stress, decreases intracellular survival, and suppresses cytokine secretion in macrophages. Transcriptomic and lipidomic analyses revealed a metabolic downshift in the B11 overexpression strain, characterized by reduced levels of TAG. Furthermore, transmission electron microscopy showed that the B11 overexpression strain exhibited decreased cell wall thickness, leading to reduced biofilm formation and altered cell wall permeability. Additionally, we observed that B11 regulated certain target genes but did not directly bind to those proteins tested.

Conclusions: Taken together, these findings suggest that B11 plays important roles in Mycobacterium survival under antibiotic and SDS stresses, TAG accumulation, and contributes to antibiotic sensitivity through altered cell wall permeability.