DNA supercoiling contributes to disconnect σ^S accumulation from σ^S‐dependent transcription in Escherichia coli

The sigmaS subunit of RNA polymerase is a key regulator of Escherichia coli transcription in stress conditions. sigmaS accumulates in cells subjected to stresses such as an osmotic upshift or the entry into stationary phase. We show here that, at elevated osmolarity, sigmaS accumulates long before the beginning of the sigmaS-dependent induction of osmEp, one of its target promoters. A combination of in vivo and in vitro evidence indicates that a...