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SpoT-triggered stringent response controls usp gene expression in Pseudomonas aeruginosa
Nelli Boes1, Kerstin Schreiber, Max Schobert
1Institute of Microbiology, Technische Universität Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany.
Journal of Bacteriology
|September 9, 2008
Summary
Pseudomonas aeruginosa universal stress proteins (Usps) are regulated by Anr under anaerobic conditions. Stationary phase expression also involves the stringent response and alkaline pH, mediated by SpoT.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Physiology
Background:
- Universal stress proteins (Usps) in Pseudomonas aeruginosa, such as UspK and UspN, are crucial for survival under anaerobic energy stress.
- Gene expression for these Usps is primarily regulated by the oxygen-sensing regulator Anr.
Purpose of the Study:
- To investigate the regulation of uspN and three additional P. aeruginosa usp genes (uspL, uspM, uspO).
- To elucidate the role of Anr, stringent response, and environmental factors in regulating usp gene expression during anaerobic conditions and stationary phase.
Main Methods:
- Utilized promoter-lacZ fusions to monitor gene expression.
- Constructed and analyzed a P. aeruginosa triple mutant (Deltaanr DeltarelA DeltaspoT).
- Quantified guanosine polyphosphate (pppGpp and ppGpp) levels using thin-layer chromatography.
Main Results:
- Anr induces uspL, uspM, and uspO expression under anaerobic conditions.
- Stationary phase induction of these genes was abolished in the Deltaanr DeltarelA DeltaspoT mutant.
- ppGpp accumulation in stationary phase was dependent on SpoT, not RelA.
- Alkaline pH in LB medium influences ppGpp accumulation during stationary phase.
Conclusions:
- Anr is a key regulator for usp gene expression under anaerobic conditions.
- The stringent response, specifically SpoT-mediated ppGpp accumulation, and alkaline pH play significant roles in regulating usp gene expression during stationary phase in P. aeruginosa.
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