The σ²⁴ Subunit of Escherichia coli RNA Polymerase Can Induce Transcriptional Pausing in vitro

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A. B. Shikalov¹, D. M. Esyunina¹, D. V. Pupov¹, A. V. Kulbachinskiy¹, and I. V. Petushkov^1,a*

¹Institute of Molecular Genetics, Russian Academy of Sciences, 123182 Moscow, Russia

^* To whom correspondence should be addressed.

Received November 2, 2018; Revised December 5, 2018; Accepted December 12, 2018

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The bacterium Escherichia coli has seven σ subunits that bind core RNA polymerase and are necessary for promoter recognition. It was previously shown that the σ⁷⁰ and σ³⁸ subunits can also interact with the transcription elongation complex (TEC) and stimulate pausing by recognizing DNA sequences similar to the –10 element of promoters. In this study, we analyzed the ability of the σ³², σ²⁸, and σ²⁴ subunits to induce pauses in reconstituted TECs containing corresponding –10 consensus elements. It was found that the σ²⁴ subunit can induce a transcriptional pause depending on the presence of the –10 element. Pause formation is suppressed by the Gre factors, suggesting that the paused complex adopts a backtracked conformation. Some natural promoters contain potential signals of σ²⁴-dependent pauses in the initially transcribed regions, suggesting that such pauses may have regulatory functions in transcription.

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KEY WORDS: transcriptional pausing, RNA polymerase, alternative σ factors, Gre proteins

DOI: 10.1134/S0006297919040102

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