Multiple sources of slow activity fluctuations in a bacterial chemosensory network
Abstract
Cellular networks are intrinsically subject to stochastic fluctuations, but analysis of the resulting noise remained largely limited to gene expression. The pathway controlling chemotaxis of Escherichia coli provides one example where posttranslational signaling noise has been deduced from cellular behavior. This noise was proposed to result from stochasticity in chemoreceptor methylation, and it is believed to enhance environment exploration by bacteria. Here we combined single-cell FRET measurements with analysis based on the fluctuation-dissipation theorem (FDT) to characterize origins of activity fluctuations within the chemotaxis pathway. We observed surprisingly large methylation-independent thermal fluctuations of receptor activity, which contribute to noise comparably to the energy-consuming methylation dynamics. Interactions between clustered receptors involved in amplification of chemotactic signals are also necessary to produce the observed large activity fluctuations. Our work thus shows that the high response sensitivity of this cellular pathway also increases its susceptibility to noise, from thermal and out-of-equilibrium processes.
Article and author information
Author details
Funding
European Research Council (294761-MicRobE)
- Remy Colin
- Christelle Rosazza
- Victor Sourjik
German-Israeli Project Cooperation (SO568/1-1)
- Remy Colin
- Christelle Rosazza
- Victor Sourjik
German-Israeli Project Cooperation (AM441/1-1)
- Ady Vaknin
Max-Planck-Institut für Terrestrische Mikrobiologie (Open-access funding)
- Remy Colin
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2017, Colin et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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