This Article Full Text Full Text (PDF) Other Versions of this Article: JB.01813-06v1 189/9/3403    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Turner, E. C. Articles by Dorman, C. J. Search for Related Content PubMed PubMed Citation Articles by Turner, E. C. Articles by Dorman, C. J.

H-NS Antagonism in Shigella flexneri by VirB, a Virulence Gene Transcription Regulator That Is Closely Related to Plasmid Partition Factors

Department of Microbiology, Trinity College Dublin, Dublin 2, Ireland

Received 1 December 2006/ Accepted 9 February 2007

The VirB protein of Shigella flexneri is a positive regulator of the major virulence operons of this enteroinvasive intracellular pathogen. VirB resembles no other transcription factor but is strongly homologous to plasmid partition proteins. We found that the binding of the VirB protein to the promoter region of the icsB virulence gene induced hypersensitivity to cleavage by DNase I over a region to which the H-NS repressor protein binds and completely abolished the protection of this sequence from DNase I by H-NS. In the absence of H-NS, the VirB protein had no additive effect on the ability of the icsB promoter to form an open transcription complex, indicating that VirB is not involved in the recruitment of RNA polymerase to the promoter or in open complex formation. Similarly, VirB did not stimulate promoter function in an in vitro transcription assay but acted as an antagonist of H-NS-mediated repression. A sequence located upstream of the icsB promoter and related to cis-acting elements involved in plasmid partitioning was required for promoter derepression by VirB. Alterations to one heptameric motif within this DNA sequence attenuated VirB binding and derepression of icsB transcription.

Published ahead of print on 16 February 2007.

This article has been cited by other articles:

• 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]  
• Ravin, N. V., Rech, J., Lane, D. (2008). Extended Function of Plasmid Partition Genes: the Sop System of Linear Phage-Plasmid N15 Facilitates Late Gene Expression. J. Bacteriol. 190: 3538-3545 [Abstract] [Full Text]  
• Perez, J. C., Latifi, T., Groisman, E. A. (2008). Overcoming H-NS-mediated Transcriptional Silencing of Horizontally Acquired Genes by the PhoP and SlyA Proteins in Salmonella enterica. J. Biol. Chem. 283: 10773-10783 [Abstract] [Full Text]  
• Stratmann, T., Madhusudan, S., Schnetz, K. (2008). Regulation of the yjjQ-bglJ Operon, Encoding LuxR-Type Transcription Factors, and the Divergent yjjP Gene by H-NS and LeuO. J. Bacteriol. 190: 926-935 [Abstract] [Full Text]  
• McFarland, K. A., Lucchini, S., Hinton, J. C. D., Dorman, C. J. (2008). The Leucine-Responsive Regulatory Protein, Lrp, Activates Transcription of the fim Operon in Salmonella enterica Serovar Typhimurium via the fimZ Regulatory Gene. J. Bacteriol. 190: 602-612 [Abstract] [Full Text]  
• Vallet-Gely, I., Sharp, J. S., Dove, S. L. (2007). Local and Global Regulators Linking Anaerobiosis to cupA Fimbrial Gene Expression in Pseudomonas aeruginosa. J. Bacteriol. 189: 8667-8676 [Abstract] [Full Text]  
• Lang, B., Blot, N., Bouffartigues, E., Buckle, M., Geertz, M., Gualerzi, C. O., Mavathur, R., Muskhelishvili, G., Pon, C. L., Rimsky, S., Stella, S., Babu, M. M., Travers, A. (2007). High-affinity DNA binding sites for H-NS provide a molecular basis for selective silencing within proteobacterial genomes. Nucleic Acids Res 35: 6330-6337 [Abstract] [Full Text]