Probing the Bacterial Flagellar Motor using Temperature Control

Abstract

Accurate temperature control is useful to probe different energetic and kinetic regimes of any molecular motor. Here we use a peltier-cooled objective to examine torque speed curves and single stator speeds of the bacterial flagellar motor in E. coli between 5C and 22C. We observe that in the high load regime, the temperature effects are minimal, whereas in the low load regime the reduction in speed due to cooling is significant. In addition we measure the membrane voltage across our temperature range to verify that the ion-motive-force does not change with temperature, as predicted from the low-load temperature independence.