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Vfr controls quorum sensing in Pseudomonas aeruginosa
A M Albus1, E C Pesci, L J Runyen-Janecky
1Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, New York 14642, USA.
Journal of Bacteriology
|June 1, 1997
Summary
Pseudomonas aeruginosa lasR gene expression is cell density-dependent, regulated by Vfr. This quorum sensing control is crucial for understanding virulence factor regulation in this bacterium.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Genetics
Background:
- Pseudomonas aeruginosa utilizes quorum sensing for cell density-dependent gene regulation.
- The lasR gene encodes a transcriptional activator at the top of the quorum-sensing hierarchy, controlling virulence factors.
- Understanding lasR regulation is key to deciphering P. aeruginosa quorum sensing.
Purpose of the Study:
- To investigate the transcriptional control mechanisms of the lasR gene in P. aeruginosa.
- To identify transcriptional start sites and regulatory elements of lasR.
- To determine the role of Vfr in lasR regulation.
Main Methods:
- Identification of transcriptional start sites (T1 and T2) for lasR.
- Construction and analysis of transcriptional lasRp-lacZ fusions in P. aeruginosa.
- Utilizing P. aeruginosa mutant studies and gel retardation assays.
Main Results:
- Two distinct transcriptional start sites for lasR were identified.
- lasR expression is cell density-dependent, increasing during late log-phase and peaking in stationary phase.
- Vfr, a homolog of E. coli CRP, mediates lasR regulation via a CRP-binding consensus sequence in the promoter.
Conclusions:
- lasR expression in P. aeruginosa is tightly regulated in a cell density-dependent manner.
- Vfr plays a critical role in controlling lasR transcription, linking cyclic AMP receptor protein (CRP) signaling to quorum sensing.
- This study elucidates a key regulatory step in the P. aeruginosa quorum-sensing network.