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The Bacillus subtilis sin operon: an evolvable network motif
Christopher A Voigt1, Denise M Wolf, Adam P Arkin
1Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. cavoigt@picasso.ucsf.edu
Genetics
|October 7, 2004
Summary
The protein-antagonist operon motif enables diverse gene regulation, acting as a tunable bistable switch. This adaptable genetic circuit can evolve into various functions, demonstrating evolutionary convergence.
Area of Science:
- Microbiology
- Systems Biology
- Evolutionary Biology
Background:
- The protein-antagonist gene arrangement within an operon allows for differential control of gene activities.
- This regulatory motif is found across evolutionarily diverse pathways, suggesting a conserved functional role.
Purpose of the Study:
- To investigate the regulatory functions and evolutionary potential of the protein-antagonist operon motif.
- To model the sin operon from Bacillus subtilis sporulation pathway to understand circuit dynamics.
Main Methods:
- Developed a theoretical model of the sin operon.
- Parameterized the model using existing literature data.
- Employed bifurcation analyses to identify potential circuit functions.
Main Results:
- The motif can function as a bistable switch with adjustable thresholds and population heterogeneity.
- Minor parameter changes can shift the circuit's behavior to graded response, oscillation, or pulse generation.
- Phylogenetic analysis revealed conserved variations in DNA regions controlling switch thresholds.
Conclusions:
- The protein-antagonist operon motif exhibits significant dynamical plasticity, enabling diverse regulatory outputs.
- This motif represents an evolutionarily convergent design, selected for both immediate function and adaptability.
- Variations in Bacillus species genomes suggest selection for tunable regulatory thresholds.