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Complex dynamics of chaperone-protein interactions under cellular stress
Igor F Tsigelny1, Sanjay K Nigam
1Department of Chemistry and Biochemistry, and San Diego Supercomputer Center, University ofCalifornia, San Diego, La Jolla, CA, USA. itsigeln@ucsd.edu
Cell Biochemistry and Biophysics
|June 24, 2004
Summary
Cellular protein folding stability depends on thresholds for ATP, chaperones, and degradation. Maintaining sufficient ATP levels and effective degradation pathways are crucial for preventing instability during cellular stress.
Area of Science:
- Cellular Biology
- Biophysics
- Systems Biology
Background:
- Cellular protein folding is a complex process regulated by molecular chaperones and energy (ATP).
- Protein misfolding and aggregation are implicated in various diseases, particularly under cellular stress conditions like ischemia.
- Understanding the dynamics of protein folding networks is crucial for developing therapeutic strategies.
Purpose of the Study:
- To develop a minimalistic mathematical model of cellular protein folding dynamics.
- To analyze the network's behavior under simulated stress (ATP depletion) and varying chaperone/degradation levels.
- To identify critical thresholds for ATP, chaperones, and degradation that maintain cellular stability.
Main Methods:
- Developed a generalizable network model based on protein-chaperone-ATP interactions.
- Modeled protein folding dynamics as a predator-prey system.
- Simulated normal physiological conditions, ATP depletion (ischemia), chaperone induction, and proteasome inhibition.
Main Results:
- A critical ATP threshold was identified; below it, complex behaviors (oscillations) emerge.
- Acute ATP drops near the threshold induce persistent oscillations, but recovery is possible with sufficient ATP increase.
- Increased chaperone levels shortened recovery time post-stress but didn't alter basal or stress-induced complex behavior.
- Inhibition of protein degradation shifted the ATP threshold, increasing system instability during ATP depletion.
Conclusions:
- Cellular protein folding dynamics exhibit distinct thresholds for ATP, chaperones, and degradation.
- Deviations outside these thresholds lead to system instability, particularly under stress.
- Chaperone induction may protect cells by mitigating instability following stress insults.