The regulatory role of anti-sigma factor, RsbW, in Clostridioides difficile stress response, persistence and infection

Abstract

The anaerobic pathogen Clostridioides difficile, which is a primary cause of antibiotic-associated diarrhoea, faces a variety of stresses in the environment and in the mammalian gut. To cope with environmental stresses, it uses the alternative sigma factor B (σB) to modulate gene transcription, which is regulated by an anti-sigma factor, RsbW. To understand the role of RsbW in C. difficile physiology, a rsbW mutant (ΔrsbW) where σB is always on, was generated. ΔrsbW did not have deleterious fitness defects but tolerated acidic environments and detoxified reactive oxygen and nitrogen species better. ΔrsbW was defective in spore and biofilm formation, adhered better to human gut epithelia and was less virulent in a Galleria mellonella infection model. A transcriptomic analysis to understand this unique phenotype showed a change in expression of some σB-controlled genes along with several non-σB controlled genes. Interestingly, the sinRR locus that encodes a pleiotropic regulator, was highly upregulated in ΔrsbW indicating a potential indirect role for σB or RsbW in control of sinRR. Furthermore, the unexpected lower intracellular levels of σB observed suggest post translational control mechanisms. Our study thus provides new insight into the regulatory role of RsbW and the complexity of regulatory networks in C. difficile.

Distinct impacts of each anti-anti-sigma factor ortholog of the chlamydial Rsb partner switching mechanism on development inChlamydia trachomatis

“…Regulator of Sigma B, or Rsb, is a well characterized PSM mostly found in Gram positive bacteria where it is used to sequester the availability of σ B in response to environmental or energy stressors (8)(9)(10)(11)(12)(13). Release of the regulated sigma factor allows for transcriptional responses that can lead to developmental changes including spore formation, activation of virulence genes, motility, biofilm formation, or initiation of various stress response pathways (14)(15)(16)(17)(18)(19)(20)(21)(22). Nominally, a PSM is composed of an anti-sigma factor with kinase activity (ASF; RsbW), a sensor phosphatase (RsbU), and an anti-anti-sigma factor (AASF; RsbV) that is the substrate for both RsbW and RsbU (23,24).…”