Abstract
BackgroundHypoxic stress plays a critical role in the persistence of Mycobacterium tuberculosis (Mtb) infection, but the mechanisms underlying this adaptive response remain ill defined.Material and methodsIn this study, using M. marinum as a surrogate, we analyzed hypoxic responses at the transcriptional level by Cappable-seq and regular RNA-seq analyses.ResultsA total of 6808 transcriptional start sites (TSSs) were identified under normoxic and hypoxic conditions. Among these TSSs, 1112 were upregulated and 1265 were downregulated in response to hypoxic stress. Using SigE-recognized consensus sequence, we identified 59 SigE-dependent promoters and all were upregulated under hypoxic stress, suggesting an important role for SigE in this process. We also compared the performance of Cappable-seq and regular RNA-seq using the same RNA samples collected from normoxic and hypoxic conditions, and confirmed that Cappable-seq is a valuable approach for global transcriptional regulation analyses.ConclusionsOur results provide insights and information for further characterization of responses to hypoxia in mycobacteria, and prove that Cappable-seq is a valuable approach for global transcriptional studies in mycobacteria.
Highlights
Mycobacterium tuberculosis (Mtb), the etiologic agent of tuberculosis (TB), is one of the most successful bacterial pathogens of humans
Hypoxic treatment of M. marinum To test the hypoxic response of M. marinum, we applied the Wayne low-oxygen model to mimic hypoxic conditions [3, 6]
Colony forming units (CFU) were increased approximately 3-fold after 24 h under oxygen limitation (Fig. 1b), suggesting that the cells successfully coped with hypoxic stress
Summary
Mycobacterium tuberculosis (Mtb), the etiologic agent of tuberculosis (TB), is one of the most successful bacterial pathogens of humans. Through inhalation of aerosol droplets containing bacilli, Mtb reaches lung airways and is engulfed by alveolar macrophages, which recruit mononuclear cells and T lymphocytes to form granulomas [2]. In both macrophages and Several in vitro models have been established to investigate how Mtb adapts to hypoxic stress, such as the Wayne model [6] and the defined hypoxia model [7, 8]. In the Wayne model, bacterial cells are grown in sealed and stirred tubes with a defined headspace-to-culture ratio, allowing the gradual exhaustion of oxygen [6]. Hypoxic stress plays a critical role in the persistence of Mycobacterium tuberculosis (Mtb) infection, but the mechanisms underlying this adaptive response remain ill defined
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