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A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
Published on: February 19, 2019
Temperature-responsive sensing regulates biocontrol factor expression in Pseudomonas fluorescens CHA0.
Bérénice Humair1, Nicolas González, Dimitris Mossialos
1Département de Microbiologie Fondamentale, Université de Lausanne, Lausanne, Switzerland.
The ISME Journal
|May 8, 2009
Summary
The Gac/Rsm pathway in Pseudomonas fluorescens CHA0 regulates biocontrol factors. Temperature affects this pathway via the RetS sensor kinase, impacting biocontrol and stress response gene expression.
Area of Science:
- Microbiology
- Molecular Biology
- Plant Pathology
Background:
- The Gac/Rsm pathway in Pseudomonas fluorescens CHA0 is crucial for producing biocontrol factors and responding to oxidative stress via RpoS.
- This pathway involves the GacS/GacA two-component system, regulating small RNAs (RsmX, RsmY, RsmZ) that counteract translational repression of biocontrol factor genes.
Purpose of the Study:
- To investigate the influence of environmental temperature on the Gac/Rsm signal transduction pathway in P. fluorescens CHA0.
- To elucidate the roles of sensor kinases RetS and LadS in temperature-dependent regulation of biocontrol factor synthesis.
Main Methods:
- Gene expression analysis of biocontrol factors (phlA, hcnA) and rpoS at different temperatures (30°C vs. 35°C).
- Construction and analysis of mutant strains (gacS, gacA, retS, ladS) to assess gene regulation.
- Epistasis analysis to determine the hierarchical relationships between sensor kinases and the Gac/Rsm system.
Main Results:
- Biocontrol factor and rpoS gene expression were significantly reduced at 35°C compared to 30°C.
- This thermosensitivity was dependent on the sensor kinase RetS, which antagonizes the GacS/GacA system.
- The sensor kinase LadS did not appear to contribute to thermosensitivity, and mutations in gacS or gacA overruled retS and ladS mutations.
Conclusions:
- Environmental temperature modulates the Gac/Rsm pathway output in P. fluorescens CHA0, primarily through the RetS sensor kinase.
- The RetS-GacS interaction is sensitive to temperature, influencing the expression of biocontrol factors and RpoS.
- This study provides insights into the temperature-dependent regulation of bacterial biocontrol mechanisms.
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