Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

65-POS Board 33 Direct Measurement of Coupling in the Bacterial Flagellar Motor

Jasmine A. Nirody 1,2 , Jordan O. Juritz 2 , Ren Chong Lim 3 , Chien-Jung Lo 4 , Richard M. Berry 2 . 1 University of California, Berkeley, Berkeley, CA, USA, 2 University of Oxford, Oxford, United Kingdom, 3 Universiti Brunei Darussalam, Bandar Seri Begawan, Brunei Darussalam, 4 National Central University, Taoyuan City, Taiwan. The bacterial flagellar motor (BFM), which drives the rotation of the flagellar filament and drives locomotion in many species of bacteria, obtains its energy from the transmembrane gradient of ions (generally, either H + or Na + ). Most models have thus far assumed a tightly- coupled mechanism, in that each full revolution of the motor is driven by a fixed number of ions. However, recent experiments showing that the number of active torque-generating units (stators) in the BFM varies across applied loads has brought many previous assumptions, including the coupling between ion flux and motor rotation, into question. Here, we use a sodium ion fluorescence indicator, Sodium Green, that can be used to make rapid measurements of internal sodium concentration in single cells to quantify sodium flux in Escherichia coli. This system will provide the first direct measurement of the coupling ratio between ion flux and motor rotation in the flagellar motor.

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