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Robust and sensitive control of a quorum-sensing circuit by two interlocked feedback loops
Joshua W Williams1, Xiaohui Cui, Andre Levchenko
1Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
Molecular Systems Biology
|December 20, 2008
Summary
Vibrio fischeri uses a LuxR autoregulatory feedback loop to control lux operon activation. This mechanism enhances sensitivity to autoinducer signals, ensuring a robust and switch-like response in bacterial quorum sensing.
Area of Science:
- Bacterial genetics and molecular biology
- Microbial physiology and signaling
- Systems biology and gene regulation
Background:
- Quorum sensing (QS) in Vibrio fischeri relies on a rapid switch in lux operon induction.
- LuxR, an autoinducer (AI)-dependent regulator, controls the lux operon, which includes AI synthase, forming a positive feedback loop.
Purpose of the Study:
- To investigate the role of a LuxR autoregulatory feedback loop in Vibrio fischeri QS.
- To understand how LuxR autoregulation contributes to the robustness and switch-like behavior of the lux operon induction.
Main Methods:
- Combination of mathematical modeling and experimental analyses.
- Utilized synthetic lux gene fragments with and without the AI synthase gene.
Main Results:
- Evidence supports a LuxR autoregulatory feedback loop, enabling LuxR concentration to increase during lux activation.
- Elevated LuxR levels enhance sensitivity to AI, promote induction, and buffer against AI fluctuations, leading to robust hysteresis.
- LuxR autoregulation allows for distinct cellular responses within the same population.
Conclusions:
- LuxR autoregulation is a key mechanism for achieving a sharp, switch-like response in Vibrio fischeri quorum sensing.
- This autoregulation confers robustness and hysteresis to the QS system, enabling distinct cellular behaviors.
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