Optimal control of the F1-ATPase molecular motor

by Dr Deepak Gupta (Simon Fraser University, Canada)

Monday 17 Oct 2022, 15:45 → 16:45 Europe/Stockholm

Albano 3: 6228 - Mega (22 seats) (Albano Building 3)

zoom link : https://stockholmuniversity.zoom.us/j/622224375

A biomolecular motor composed of protein complexes exchanges energy, matter, and information with its surrounding. Despite being in contact with a fluctuating environment, it performs (on average) a directed motion in accordance with the second law by transducing chemical energy stored in the surrounding environment. Among several biomolecular motors FoF1-ATP synthase has gained much attention due to its high efficiency. It produces ~95% of the cellular ATP (adenosine triphosphate) from ADP (adenosine diphosphate) and Pi (inorganic phosphate). The membrane-embedded Fo-unit utilizes energy from proton flux to rotate F1-unit's γ-crankshaft and synthesizes ATP molecules. Since γ-crankshaft rotates as fast as ~350 revolutions per second, it remains a puzzle how FoF1 transduces free energy in highly efficient manner. One possible way to investigate this is to uncover the functional principle of that particular unit where ATP is synthesized, i.e., F1-ATPase. To this end, we focus on an isolated F1-ATPase, which can also be controlled in an experimental setup. We design a control protocol (mimicking Fo operation) by which the unit's γ-crankshaft can be rotated to synthesize ATP at low dissipation. We follow a near-equilibrium framework to construct a non-trivial designed protocol. Then, we rotate the crankshaft with this designed protocol to compute dissipation. Our analysis reveals that the designed protocol dissipates a less amount of energy in comparison to a constant velocity protocol for a wide range of protocol durations.