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Optimal choice between feedforward and feedback control in gene expression to cope with unpredictable danger
Emi Shudo1, Patsy Haccou, Yoh Iwasa
1Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan. shudo@bio-math10.biology.kyushu-u.ac.jp
Journal of Theoretical Biology
|June 20, 2003
Summary
Organisms use different strategies to cope with environmental dangers like heat shocks. This study finds that immediate heat-shock protein production (feedforward control) is always beneficial, with additional proteins produced only when damage is severe.
Area of Science:
- Cellular biology
- Biophysics
- Systems biology
Background:
- Organisms face environmental risks requiring damage control mechanisms.
- Heat shocks can denature proteins, necessitating repair via heat-shock proteins (HSP).
- Two HSP production pathways exist: immediate feedforward and delayed feedback control.
Purpose of the Study:
- To determine optimal strategies for damage control using different response pathways.
- To analyze the trade-offs between damage and production costs for HSP.
- To model the conditions favoring feedforward versus feedback control in microbes like E. coli.
Main Methods:
- Mathematical modeling of cellular damage control.
- Analysis of optimal control strategies balancing damage and cost.
- Simulation of microbial responses to heat shock.
Main Results:
- Feedforward control for HSP production is consistently optimal.
- Feedback control is beneficial only when denatured protein abundance is high.
- The optimal strategy depends on factors like time delay, HSP effectiveness, and damage severity.
Conclusions:
- A combined feedforward and feedback approach optimizes cellular defense.
- Immediate HSP production is crucial, with feedback acting as a secondary response.
- The decision to use feedback depends on the predicted severity of protein damage.