Introduction Most bacterial genes are transcribed by the RNA polymerase (RNAP) holoenzyme that includes a primary sigma subunit (σ factor referred to as RpoD/σ70 in Escherichia coli and SigA/σA in many other bacteria) that is responsible for the transcription of housekeeping genes. Transcription of the genes involved in starvation, stationary phase, and general stress response largely depends on the presence of the primary-like σ factor usually named σΒ in Gram-positive bacteria.
