Differential Affinity and Catalytic Activity of CheZ in E. coli Chemotaxis
| Autor: | Pieter Rein ten Wolde, Siebe B. van Albada |
|---|---|
| Přispěvatelé: | Theoretical Physics |
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
Biophysics/Theory and Simulation
Histidine Kinase Phosphatase Methyl-Accepting Chemotaxis Proteins Plasma protein binding Computer Science/Numerical Analysis and Theoretical Computing Biology Models Biological Cellular and Molecular Neuroscience Bacterial Proteins Genetics Escherichia coli Biochemistry/Cell Signaling and Trafficking Structures Biophysics/Cell Signaling and Trafficking Structures Receptor lcsh:QH301-705.5 Molecular Biology Ecology Evolution Behavior and Systematics Ecology Biochemistry/Theory and Simulation Kinase Chemotaxis Escherichia coli Proteins Membrane Proteins Cell biology Computational Biology/Signaling Networks lcsh:Biology (General) Computational Theory and Mathematics Biochemistry Cytoplasm Modeling and Simulation Phosphorylation Signal transduction Algorithms Protein Binding Signal Transduction Research Article |
| Zdroj: | van Albada, S B & ten Wolde, P R 2009, ' Differential Affinity and Catalytic Activity of CheZ in E. coli Chemotaxis ', PLoS Computational Biology, vol. 5, no. 5, pp. e1000378 . https://doi.org/10.1371/journal.pcbi.1000378 PLoS Computational Biology PLoS Computational Biology, 5(5). Public Library of Science PLoS Computational Biology, Vol 5, Iss 5, p e1000378 (2009) |
| ISSN: | 1553-734X |
| DOI: | 10.1371/journal.pcbi.1000378 |
| Popis: | Push–pull networks, in which two antagonistic enzymes control the activity of a messenger protein, are ubiquitous in signal transduction pathways. A classical example is the chemotaxis system of the bacterium Escherichia coli, in which the kinase CheA and the phosphatase CheZ regulate the phosphorylation level of the messenger protein CheY. Recent experiments suggest that both the kinase and the phosphatase are localized at the receptor cluster, and Vaknin and Berg recently demonstrated that the spatial distribution of the phosphatase can markedly affect the dose–response curves. We argue, using mathematical modeling, that the canonical model of the chemotaxis network cannot explain the experimental observations of Vaknin and Berg. We present a new model, in which a small fraction of the phosphatase is localized at the receptor cluster, while the remainder freely diffuses in the cytoplasm; moreover, the phosphatase at the cluster has a higher binding affinity for the messenger protein and a higher catalytic activity than the phosphatase in the cytoplasm. This model is consistent with a large body of experimental data and can explain many of the experimental observations of Vaknin and Berg. More generally, the combination of differential affinity and catalytic activity provides a generic mechanism for amplifying signals that could be exploited in other two-component signaling systems. If this model is correct, then a number of recent modeling studies, which aim to explain the chemotactic gain in terms of the activity of the receptor cluster, should be reconsidered. Author Summary In both prokaryotes and eukaryotes, extra- and intracellular signals are often processed by biochemical networks in which two enzymes together control the activity of a messenger protein via opposite modification reactions. A well-known example is the chemotaxis network of Escherichia coli that controls the swimming behavior of the bacterium in response to chemical stimuli. Recent experiments suggest that the two counteracting enzymes in this network are colocalized at the receptor cluster, while experiments by Vaknin and Berg indicate that the spatial distribution of the enzymes by itself can markedly affect the response of the network. We argue using mathematical modeling that the most widely used model of the chemotaxis network is inconsistent with these experimental observations. We then present an alternative model in which part of one enzyme is colocalized with the other enzyme at the receptor cluster, while the remainder freely diffuses in the cytoplasm; moreover, the fraction at the cluster both binds more strongly to the messenger protein and modifies it faster. This model is consistent with a large number of experimental observations and provides a generic mechanism for amplifying signals. |
| Databáze: | OpenAIRE |
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