Back to Search
Start Over
Binding of Pseudomonas aeruginosa AlgZ to sites upstream of the algZ promoter leads to repression of transcription
- Source :
- Journal of bacteriology. 187(13)
- Publication Year :
- 2005
-
Abstract
- 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.
- Subjects :
- Transcription, Genetic
Operon
Molecular Sequence Data
Repressor
Biology
Microbiology
DNA-binding protein
Bacterial Proteins
Species Specificity
Transcription (biology)
Consensus Sequence
Transcriptional regulation
Binding site
Promoter Regions, Genetic
Molecular Biology
Gene
Molecular Biology of Pathogens
Binding Sites
Base Sequence
Activator (genetics)
Molecular biology
DNA-Binding Proteins
Repressor Proteins
Pseudomonas aeruginosa
Transcription Initiation Site
Protein Binding
Subjects
Details
- ISSN :
- 00219193
- Volume :
- 187
- Issue :
- 13
- Database :
- OpenAIRE
- Journal :
- Journal of bacteriology
- Accession number :
- edsair.doi.dedup.....b38dd6b5557b949046dbeafa36e219ff