A σ(B)-dependent sRNA provides a repressor function to the general stress response in Clostridioides difficile.

Hfq-dependent sRNA SrsA is integrated into the σB regulon in Clostridioides difficile, repressing sporulation regulators and Wood–Ljungdahl methyl-fixing genes during infection-relevant stress.

• Why it matters: It is unclear whether the Gammaproteobacteria paradigm—alternative-sigma-factor stress responses using sRNAs as repressors—is conserved in other bacterial phyla, especially in Firmicutes pathogens.
• What they did: The study mapped SrsA into the σB regulatory network, measured its high expression during exponential-to-stationary transition and oxidative stress, and tested repression of target genes and a conserved spore regulator family.
• The result: In an acute and relapse mouse model, SrsA contributes to disease severity and bacterial recovery after antibiotic treatment, implying σB-linked sRNA control helps coordinate sporulation and metabolism under gut stress.