Modulation of tyrT promoter activity by template supercoiling in vivo

Bowater, Richard P., Chen, Dongrong and Lilley, David M. J. (1994) Modulation of tyrT promoter activity by template supercoiling in vivo. EMBO Journal, 13 (23). pp. 5647-5655. ISSN 0261-4189

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Abstract

We have found that initiation of RNA synthesis at the tyrT promoter of Escherichia coli can be stimulated on a plasmid by a factor of 4-6 by elevation of DNA supercoiling in vivo. Increased unconstrained plasmid supercoiling was achieved by inserting the tyrT promoter upstream of the tetracycline resistance gene tetA and transformation into a topA host. Under these conditions there is marked oversupercoiling of the plasmid DNA and we have shown previously that this can lead to increased promoter activity in the topological domain created. A critical element in the formation of this domain is the coupled transcription, translation and membrane insertion of tetA and we show that all of these events are important in the stimulation of tyrT promoter activity. The magnitude of the stimulation is in reasonable agreement with that measured in vitro as a function of plasmid supercoiling, if the unconstrained level of negative supercoiling in vivo is increased from a basal level of -σ ≃ 0.022 to -σ ≃ -0.052 by transcription-induced supercoiling. The induced supercoiling is very efficient, indicating that the tyrT promoter is itself contributing to the steady-state level despite a total lack of membrane anchorage for the tyrT transcription unit. This study provides a new example of the topological coupling of promoters.

Item Type:	Article
Uncontrolled Keywords:	dna topology,rna polymerase,transcription,general neuroscience,molecular biology,general biochemistry,genetics and molecular biology,general immunology and microbiology ,/dk/atira/pure/subjectarea/asjc/2800/2800
Faculty \ School:	Faculty of Science > School of Biological Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Biosciences Teaching and Education Research Faculty of Science > Research Groups > Molecular Microbiology Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry
Related URLs:	https://www.scopus.com/pages/publication...
Depositing User:	LivePure Connector
Date Deposited:	27 May 2026 11:02
Last Modified:	27 May 2026 11:02
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103169
DOI:	10.1002/j.1460-2075.1994.tb06903.x

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