Possible roles of σ-dependent RNA polymerase pausing in transcription regulation.

The σ subunit of bacterial RNA polymerase is required for promoter recognition during transcription initiation but may also regulate transcription elongation. The principal σ70 subunit of Escherichia coli was shown to travel with RNA polymerase and induce transcriptional pausing at promoter-like motifs, with potential regulatory output. We recently demonstrated that an alternative σ38 subunit can also induce RNA polymerase pausing. Here, we outline proposed regulatory roles of σ-dependent pausing in bacteria and discuss possible interplay between alternative σ variants and regulatory factors during transcription elongation.