Redefining the Clostridioides difficile σB regulon: σB activates genes involved in detoxifying radicals that can result from the exposure to antimicrobials and hydrogen peroxide

ABSTRACT: In Gram-positive organisms the general stress response is regulated by the alternative sigma factor sigma B (σB). In C. difficile this sigma factor has been implicated in protection against stressors such as reactive oxygen species and antimicrobial compounds. Here, we show that an anti-σB antibody can be used to demonstrate overexpression of σB in C. difficile and that this overexpression is tolerated for short periods of time, despite its toxicity. Toxicity associated with σB-overexpression leads to loss of the plasmid used for anhydrotetracycline-induced σB expression. By uncoupling σB from its native regulatory network, we refined the previously proposed σB regulon and confirmed a direct role for σB in the induction of selected genes using in vitro run-off transcription reactions. Finally, using a plate-based luciferase reporter assay we demonstrated that different antibiotics and hydrogen peroxide induce genes positively regulated by σB in a manner dependent on this sigma factor. Together, our work suggests that lethal exposure to antibiotics may result in the formation of toxic radicals that lead to σB-dependent gene activation.

ORGANISM(S): Clostridioides difficile 630

PROVIDER: GSE152515 | GEO | 2020/09/07

REPOSITORIES: GEO