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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
77
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.