Multiple sources of slow activity fluctuations in a bacterial chemosensory network

Remy Colin, Christelle Rosazza, Ady Vaknin, Victor Sourjik

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


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.

Original languageAmerican English
Article numbere26796
StatePublished - 12 Dec 2017

Bibliographical note

Publisher Copyright:
© 2017, Colin et al.


  • E. coli
  • Levy walks
  • bacterial chemotaxis
  • cell networks dynamics
  • computational biology
  • fluctuation dissipation relation
  • infectious disease
  • microbiology
  • out-of-equilibrium
  • single-cell FRET
  • systems biology


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