This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hulbert, R. R.
Right arrow Articles by Taylor, R. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hulbert, R. R.
Right arrow Articles by Taylor, R. K.

 Previous Article  |  Next Article 

Journal of Bacteriology, October 2002, p. 5533-5544, Vol. 184, No. 20
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.20.5533-5544.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Mechanism of ToxT-Dependent Transcriptional Activation at the Vibrio cholerae tcpA Promoter{dagger}

Robin R. Hulbert and Ronald K. Taylor*

Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, New Hampshire 03755

Received 17 January 2002/ Accepted 21 June 2002

The AraC homolog ToxT coordinately regulates virulence gene expression in Vibrio cholerae. ToxT is required for transcriptional activation of the genes encoding cholera toxin and the toxin coregulated pilus, among others. In this work we focused on the interaction of ToxT with the tcpA promoter and investigated the mechanism of ToxT-dependent transcriptional activation at tcpA. Deletion analysis showed that a region from -95 to +2 was sufficient for ToxT binding and activation, both of which were simultaneously lost when the deletion was extended to -63. A collection of point mutations generated by error-prone PCR revealed two small regions required for ToxT-dependent transactivation. Binding studies performed with representative mutations showed that the two regions define sites at which ToxT binds to the tcpA promoter region, most likely as a dimer. Results obtained by using a rpoA truncation mutation showed that ToxT-dependent activation at tcpA involves the C-terminal domain of the RNA polymerase alpha subunit. A model of ToxT-dependent transcriptional activation at tcpA is proposed, in which ToxT interacts with two A-rich regions of tcpA centered at -72 and -51 and requires the alpha C-terminal domain of RNA polymerase.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, HB7550, Dartmouth Medical School, Hanover, NH 03755. Phone: (603) 650-1623. Fax: (603) 650-1318. E-mail: ronald.k.taylor{at}dartmouth.edu.

{dagger} For a commentary on this article, see p. 5529 in this issue.

Journal of Bacteriology, October 2002, p. 5533-5544, Vol. 184, No. 20
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.20.5533-5544.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Abuaita, B. H., Withey, J. H. (2009). Bicarbonate Induces Vibrio cholerae Virulence Gene Expression by Enhancing ToxT Activity. Infect. Immun. 77: 4111-4120 [Abstract] [Full Text]  
  • Bellair, M., Withey, J. H. (2008). Flexibility of Vibrio cholerae ToxT in Transcription Activation of Genes Having Altered Promoter Spacing. J. Bacteriol. 190: 7925-7931 [Abstract] [Full Text]  
  • Stoebel, D. M., Free, A., Dorman, C. J. (2008). Anti-silencing: overcoming H-NS-mediated repression of transcription in Gram-negative enteric bacteria. Microbiology 154: 2533-2545 [Abstract] [Full Text]  
  • Stonehouse, E., Kovacikova, G., Taylor, R. K., Skorupski, K. (2008). Integration Host Factor Positively Regulates Virulence Gene Expression in Vibrio cholerae. J. Bacteriol. 190: 4736-4748 [Abstract] [Full Text]  
  • Matson, J. S., Withey, J. H., DiRita, V. J. (2007). Regulatory Networks Controlling Vibrio cholerae Virulence Gene Expression. Infect. Immun. 75: 5542-5549 [Full Text]  
  • Navarre, W. W., McClelland, M., Libby, S. J., Fang, F. C. (2007). Silencing of xenogeneic DNA by H-NS--facilitation of lateral gene transfer in bacteria by a defense system that recognizes foreign DNA. Genes Dev. 21: 1456-1471 [Abstract] [Full Text]  
  • Shakhnovich, E. A., Hung, D. T., Pierson, E., Lee, K., Mekalanos, J. J. (2007). Virstatin inhibits dimerization of the transcriptional activator ToxT. Proc. Natl. Acad. Sci. USA 104: 2372-2377 [Abstract] [Full Text]  
  • Withey, J. H., DiRita, V. J. (2005). Vibrio cholerae ToxT Independently Activates the Divergently Transcribed aldA and tagA Genes. J. Bacteriol. 187: 7890-7900 [Abstract] [Full Text]  
  • Tischler, A. D., Camilli, A. (2005). Cyclic Diguanylate Regulates Vibrio cholerae Virulence Gene Expression. Infect. Immun. 73: 5873-5882 [Abstract] [Full Text]  
  • Sanchez, J., Medina, G., Buhse, T., Holmgren, J., Soberon-Chavez, G. (2004). Expression of Cholera Toxin under Non-AKI Conditions in Vibrio cholerae El Tor Induced by Increasing the Exposed Surface of Cultures. J. Bacteriol. 186: 1355-1361 [Abstract] [Full Text]  
  • Kovacikova, G., Lin, W., Skorupski, K. (2003). The Virulence Activator AphA Links Quorum Sensing to Pathogenesis and Physiology in Vibrio cholerae by Repressing the Expression of a Penicillin Amidase Gene on the Small Chromosome. J. Bacteriol. 185: 4825-4836 [Abstract] [Full Text]  
  • Ibarra, J. A., Villalba, M. I., Puente, J. L. (2003). Identification of the DNA Binding Sites of PerA, the Transcriptional Activator of the bfp and per Operons in Enteropathogenic Escherichia coli. J. Bacteriol. 185: 2835-2847 [Abstract] [Full Text]  
  • Egan, S. M. (2002). Growing Repertoire of AraC/XylS Activators. J. Bacteriol. 184: 5529-5532 [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»