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Prediction by promoter logic in bacterial quorum sensing
Navneet Rai1, Rajat Anand, Krishna Ramkumar
1National Centre for Biological Sciences, Tata Institute of Fundamental Research, UAS/GKVK Campus, Bangalore, India.
Plos Computational Biology
|January 26, 2012
Summary
Bacterial chemical communication (quorum sensing) uses promoter logic to control cell behavior. This study shows promoter activity predicts system responses, revealing how feedback circuits generate diverse bacterial behaviors.
Area of Science:
- Microbiology
- Systems Biology
- Biochemistry
Background:
- Quorum sensing (QS) enables bacterial cell-cell communication, regulating group behaviors like biofilm formation and virulence.
- The LuxI/LuxR system is a key proteobacterial QS paradigm involving a signaling molecule (autoinducer) and a transcriptional regulator.
- Feedback loops in QS can create smooth (monostable) or abrupt (bistable) responses, adapting to ecological needs.
Purpose of the Study:
- To demonstrate that the promoter logic of the LuxI/LuxR system inherently contains information to predict feedback loop responses.
- To investigate how promoter characteristics and feedback topology influence the dynamic behaviors of QS systems.
- To highlight the predictive power of promoter logic in understanding bacterial collective behaviors.
Main Methods:
- Theoretical modeling combined with experimental validation.
- Quantitative analysis of promoter activity as a function of LuxI and LuxR concentrations.
- Characterization of feedback loop dynamics under different topological configurations (positive/negative feedback).
Main Results:
- The promoter logic of the LuxI/LuxR system's cognate promoter (pR) quantitatively predicts the responses of feedback circuits.
- Positive feedback of LuxR and LuxI exhibit distinct system-level responses.
- A dual positive/negative feedback system demonstrates synchronized oscillations, showcasing complex dynamic behaviors.
Conclusions:
- Promoter logic is a critical determinant of bacterial quorum sensing system behavior and versatility.
- Understanding promoter logic allows prediction of macroscopic phenotypes from microscopic biochemical parameters.
- This framework advances the study of bacterial communication and synthetic biology circuit design.
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