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Wednesday, April 26 • 8:30am - 10:00am
Structural Dynamics of Subunit a in the FO Motor of E. coli ATP Synthase

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Adenosine triphosphate (ATP), the energy currency of the cell, is primarily synthesized by F1FO ATP synthase. This protein complex converts the proton motive force set up by cellular metabolism into chemical energy through a set of coupled molecular motors. The FO region of ATP synthase is embedded in the membrane, and proton translocation at the subunit a/c interface generates torque on the c ring. This mechanical rotation drives conformational changes in the catalytic sites of F1. A Brownian ratchet mechanism has been proposed for the FO motor in which the conversion of thermal motion to unidirectional motion occurs by regulating aqueous access to two compartments with different pH. However, this mechanism neglects evidence that subunit a may undergo conformational changes during ATP synthesis, which if correct, could have functional importance that sheds light on the problem of extracting torque from random motion. This study will use electron paramagnetic resonance (EPR) spectroscopy to measure structural dynamics of subunit a under various conditions. Cysteine mutations have been genetically introduced into the a subunit, and the mutant proteins will be purified and chemically modified with spin labels, which can be detected by EPR. EPR data will be analyzed with aim of inferring protein movements and integrating these into a description of the FO motor mechanism.


Wednesday April 26, 2017 8:30am - 10:00am PDT
Concourse - Wilma Sherrill Center