Tampere University of Technology

TUTCRIS Research Portal

Effects of σ factor competition are promoter initiation kinetics dependent

Research output: Contribution to journalArticleScientificpeer-review


Original languageEnglish
Pages (from-to)1281-1288
Number of pages8
JournalBiochimica et Biophysica Acta: Gene Regulatory Mechanisms
Issue number10
Publication statusPublished - 1 Oct 2016
Publication typeA1 Journal article-refereed


In Escherichia coli, the expression of a σ factor is expected to indirectly down-regulate the expression of genes recognized by another σ factor, due to σ factor competition for a limited pool of RNA polymerase core enzymes. Evidence suggests that the sensitivity of genes to indirect down-regulation differs widely. We studied the variability in this sensitivity in promoters primarily recognized by RNAP holoenzymes carrying σ70. From qPCR and live single-cell, single-RNA measurements of the transcription kinetics of several σ70-dependent promoters in various conditions and from the analysis of σ factors population-dependent models of transcription initiation, we find that, the smaller is the time-scale of the closed complex formation relative to the open complex formation, the weaker is a promoter's responsiveness to changes in σ38 numbers. We conclude that, in E. coli, a promoter's responsiveness to indirect regulation by σ factor competition is determined by the sequence-dependent kinetics of the rate limiting steps of transcription initiation.


  • Closed Complex Formation, In vivo Transcription dynamics, Open Complex Formation, Single RNA detection, σ Factors competition

Publication forum classification

Field of science, Statistics Finland