It is well known that flagellated bacteria, such as Escherichia coli, sense chemicals in their environment by a chemoreceptor and relay signals via a well-characterised signalling pathway to the flagellar motor. It is widely accepted that the signals change the rotation bias of the motor without influencing the motor speed. Here, we present results to the contrary and show that the bacteria is also capable of modulating motor speed on merely sensing a ligand. Step changes in concentration of non-metabolisable ligand cause temporary recruitment of stator units leading to a momentary increase in motor speeds. For metabolisable ligand, the combined effect of sensing and metabolism leads to higher motor speeds for longer durations. Experiments performed with mutant strains delineate the role of metabolism and sensing in the modulation of motor speed and show how speed changes along with changes in bias can significantly enhance response to changes in its environment.
All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 2, 3 and 4.
- Mahesh S Tirumkudulu
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Raymond E Goldstein, University of Cambridge, United Kingdom
- Received: September 6, 2020
- Accepted: April 3, 2021
- Accepted Manuscript published: April 6, 2021 (version 1)
© 2021, Naaz et al.
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