This Article Full Text Full Text (PDF) 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 Ramsey, D. M. Articles by Wozniak, D. J. Search for Related Content PubMed PubMed Citation Articles by Ramsey, D. M. Articles by Wozniak, D. J.

Binding of Pseudomonas aeruginosa AlgZ to Sites Upstream of the algZ Promoter Leads to Repression of Transcription

Deborah M. Ramsey, Patricia J. Baynham, and Daniel J. Wozniak^*

Department of Microbiology and Immunology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, North Carolina 27157

Received 8 December 2004/ Accepted 18 March 2005

Mucoid variants of the opportunistic pathogen Pseudomonas aeruginosa produce the exopolysaccharide alginate and colonize the respiratory tracts of cystic fibrosis patients. The genes encoding the alginate biosynthetic enzymes are clustered in a single operon, which is under tight transcriptional control. One essential activator of the alginate operon is AlgZ, a proposed ribbon-helix-helix DNA binding protein that shares 30% amino acid identity with the Mnt repressor of Salmonella enterica serovar Typhimurium bacteriophage P22. In the current study, we examined the role of AlgZ as an autoregulator. Using single-copy algZ-lacZ transcription fusions, an increase in algZ transcription was observed in an algZ mutant compared to the isogenic wild-type strain, suggesting that AlgZ may have an additional role as a repressor. To identify the AlgZ binding site, overlapping regions upstream of algZ were incubated with AlgZ and analyzed by electrophoretic mobility shift assays. Specific binding activity was localized to a region spanning from 66 to 185 base pairs upstream of the algZ transcriptional start site. Two AlgZ binding sites were defined using copper-phenanthroline footprinting and deletion analyses, with one site centered at 93 base pairs and the other centered at 161 base pairs upstream of the algZ promoter. Deletion of both binding sites resulted in the loss of AlgZ binding. These results indicate that AlgZ represses algZ transcription, and this activity is mediated by multiple AlgZ-DNA interactions.

Present address: Department of Biology, St. Edward's University, 3001 South Congress Ave., Austin, TX 78704-6489.

This article has been cited by other articles:

• Doern, C. D., Holder, R. C., Reid, S. D. (2008). Point mutations within the streptococcal regulator of virulence (Srv) alter protein-DNA interactions and Srv function. Microbiology 154: 1998-2007 [Abstract] [Full Text]  
• Belete, B., Lu, H., Wozniak, D. J. (2008). Pseudomonas aeruginosa AlgR Regulates Type IV Pilus Biosynthesis by Activating Transcription of the fimU-pilVWXY1Y2E Operon. J. Bacteriol. 190: 2023-2030 [Abstract] [Full Text]  
• Leech, A. J., Sprinkle, A., Wood, L., Wozniak, D. J., Ohman, D. E. (2008). The NtrC Family Regulator AlgB, Which Controls Alginate Biosynthesis in Mucoid Pseudomonas aeruginosa, Binds Directly to the algD Promoter. J. Bacteriol. 190: 581-589 [Abstract] [Full Text]  
• Tart, A. H., Blanks, M. J., Wozniak, D. J. (2006). The AlgT-Dependent Transcriptional Regulator AmrZ (AlgZ) Inhibits Flagellum Biosynthesis in Mucoid, Nonmotile Pseudomonas aeruginosa Cystic Fibrosis Isolates.. J. Bacteriol. 188: 6483-6489 [Abstract] [Full Text]  
• Baynham, P. J., Ramsey, D. M., Gvozdyev, B. V., Cordonnier, E. M., Wozniak, D. J. (2006). The Pseudomonas aeruginosa Ribbon-Helix-Helix DNA-Binding Protein AlgZ (AmrZ) Controls Twitching Motility and Biogenesis of Type IV Pili. J. Bacteriol. 188: 132-140 [Abstract] [Full Text]  
• Ernst, F. D., Kuipers, E. J., Heijens, A., Sarwari, R., Stoof, J., Penn, C. W., Kusters, J. G., van Vliet, A. H. M. (2005). The Nickel-Responsive Regulator NikR Controls Activation and Repression of Gene Transcription in Helicobacter pylori. Infect. Immun. 73: 7252-7258 [Abstract] [Full Text]