Colloquium
Department of Physics, NCU
Bacterial thermotaxis: sensing, control and motility
Speaker
Prof. Hanna Salman
University of Pittsburgh
Date 2015.9.22(Tue)
Time 14:00
Place S4-625
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Bacteria sense signals from their environment and control their response accordingly. Thermotaxis – the motion towards more favorable temperature – is crucial for the survival of microorganisms that cannot control their internal temperature. I will review our work on the various stages of thermotaxis in bacteria, from sensing to motility, which utilizes experimental systems developed specifically to monitor their behavior in temperature gradients and study their sensing and response to temperature changes.
Our results reveal a sensitive mechanism of navigation control that relies on the competition between two receptors with opposing responses. This mechanism allows the bacteria to localize themselves at a specific temperature, which differs from cell to cell, suggesting an evolutionary benefit to diversity, and allows us to quantify the system’s sensitivity.
The sensed temperature signal is ultimately translated into motion powered by the bacterial flagellar motor. Using temporal changes in temperature we have discovered a resonance effect in the dynamics of the motor’s angular velocity in response to thermal oscillations, providing new insight into the rich and complex internal dynamics of the motor.
These results open new avenues of research to better understand the design principles behind biological temperature sensors in general, and the overall structure of bacterial thermotaxis from input signal all the way to output motion.