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Downregulation of the Escherichia coli guaB promoter by upstream-bound cyclic AMP receptor protein

Husnain, S., Busby, S.J.W. and Thomas, M.S. (2009) Downregulation of the Escherichia coli guaB promoter by upstream-bound cyclic AMP receptor protein. Journal of Bacteriology, 191 (19). pp. 6094-6104. ISSN 0021-9193

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Abstract

The Escherichia coli guaB promoter (P-guaB) is responsible for directing transcription of the guaB and guaA genes, which specify the biosynthesis of the nucleotide GMP. P-guaB is subject to growth rate-dependent control (GRDC) and possesses an UP element that is required for this regulation. In addition, PguaB contains a discriminator, three binding sites for the nucleoid-associated protein FIS, and putative binding sites for the regulatory proteins DnaA, PurR, and cyclic AMP receptor protein (CRP). Here we show that the CRP-cyclic AMP (cAMP) complex binds to a site located over 100 bp upstream of the guaB transcription start site, where it serves to downregulate P-guaB. The CRP-mediated repression of P-guaB activity increases in media that support lower growth rates. Inactivation of the crp or cyaA gene or ablation/translocation of the CRP site relieves repression by CRP and results in a loss of GRDC of P-guaB. Thus, GRDC of P-guaB involves a progressive increase in CRP-mediated repression of the promoter as the growth rate decreases. Our results also suggest that the CRP-cAMP complex does not direct GRDC at P-guaB and that at least one other regulatory factor is required for conferring GRDC on this promoter. However, PurR and DnaA are not required for this regulatory mechanism.

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 American Society of Microbiology. This is an author produced version of a paper subsequently published in Journal of Bacteriology. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: C-Terminal Domain; Rate-Dependent Regulation; Catabolite Activator Protein; Ribosomal-RNA Transcription; Polymerase Alpha-Subunit; Growth-Rate Regulation; Bacterial Transcription; Nucleoprotein Complexes; Negative Control; Cloning Vectors
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Biological Sciences (Sheffield) > Department of Biomedical Science (Sheffield)
The University of Sheffield > Faculty of Medicine, Dentistry and Health (Sheffield) > School of Medicine (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 06 Oct 2009 13:57
Last Modified: 08 Feb 2013 16:59
Published Version: http://dx.doi.org/10.1128/JB.00672-09
Status: Published
Publisher: American Society of Microbiology
Refereed: Yes
Identification Number: 10.1128/JB.00672-09
URI: http://eprints.whiterose.ac.uk/id/eprint/9826

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