Robust signal processing in living cells.
Cellular signaling networks have evolved an astonishing ability to function reliably and with high fidelity in uncertain environments. A crucial prerequisite for the high precision exhibited by many signaling circuits is their ability to keep the concentrations of active signaling compounds within tightly defined bounds, despite strong stochastic fluctuations in copy numbers and other detrimental influences. Based on a simple mathematical formalism, we identify topological organizing principles that facilitate such robust control of intracellular concentrations in the face of multifarious perturbations. Our framework allows us to judge whether a multiple-input-multiple-output reaction network is robust against large perturbations of network parameters and enables the predictive design of perfectly robust synthetic network architectures. Utilizing the Escherichia coli chemotaxis pathway as a hallmark example, we provide experimental evidence that our framework indeed allows us to unravel the topological organization of robust signaling. We demonstrate that the specific organization of the pathway allows the system to maintain global concentration robustness of the diffusible response regulator CheY with respect to several dominant perturbations. Our framework provides a counterpoint to the hypothesis that cellular function relies on an extensive machinery to fine-tune or control intracellular parameters. Rather, we suggest that for a large class of perturbations, there exists an appropriate topology that renders the network output invariant to the respective perturbations.
Institute for Theoretical Biology, Humboldt University of Berlin, Berlin, Germany. ralf.steuer@hu-berlin.de
Ralf
R
Steuer
Steffen
S
Waldherr
Victor
V
Sourjik
Markus
M
Kollmann
D001426:Bacterial Proteins / Q000502:physiology; D002450:Cell Communication / Q000502:physiology; D002633:Chemotaxis / Q000502:physiology; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000502:physiology; D000072236:Methyl-Accepting Chemotaxis Proteins; D008954:Models, Biological; D015398:Signal Transduction / Q000502:physiology*; D049490:Systems Biology
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli