Biophysical Society Conference | Tahoe 2024

Molecular Biophysics of Membranes

Poster Abstracts

41-POS Board 21 EXTRACTING SHORT-LIVED STATES IN SINGLE F-ATPASE MOLECULAR MOTORS Sandor Volkan-Kacso 1,2 ; 1 California Inst. of Technology, Pasadena, CA, USA 2 Azusa Pacific University, Mathematics, Physics and Statistics, Azusa, CA, USA Recently, we proposed a method to analyze fast rotation trajectories in F1-ATPase using the distribution of angular velocity. The analysis involves the transitions during the stepping between pauses. A theoretical-computational approach is used to model the fluctuation of the imaging probe as the molecular motor undergoes stepping rotation. A key quantity in this method is the angular velocity vs. rotation angle extracted from both experimental data and computer simulations. When applying the method on Thermophilic Bacillus F1-ATPase rotation data, we detected the presence of a short-lived substep previously not detectable in the histograms. The comparison between the experimental and theory reveals that an 80 O substep of the “concerted” ATP binding and ADP release involves an intermediate state reminiscent of a 3 occupancy structure. Its lifetime (~10 µs) is about six orders of magnitude smaller than the lifetime for spontaneous ADP release. By detecting this short-lived state the method provides “temporal super-resolution”. Most recently, this method was applied to single-molecule imaging data from Paracoccus Denitrificans F1-ATPase and it yielded a similar hidden state in the transitions between dwells. Our recent findings indicate a common mechanism for the acceleration of ADP release in the F1-ATPase motor of the two species.

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