The Bacterial Flagellar Motor: a biological nano-scale actuator and sensor – FlagMotor

Many bacteria are capable of active movement in liquid environment, which confers them a great advantage for survival. The Bacterial Flagellar Motor (BFM) is the powerful molecular machine that drives this movement by rotating each flagellum at its base, by switching the direction of rotation in a few milliseconds, and by adapting in different ways to the external environment. As recent results show, the motor is unveiling a surprisingly rich dynamical behavior, both in its output power, in its internal components, and its mechanisms, which we are only starting to understand. Part of the complexity of the BFM comes from the fact that its energy source is itself the result of a complex out-of-equilibrium process. The BFM is in fact an electrical motor, consuming energy from the transmembrane potential difference, the Proton Motive Force (PMF), generated and sustained during cellular respiration. The PMF has a central role in several cellular processes, which it serves in parallel, the activity of the BFM and ATP synthesis being the main examples. From a physical point of view, the PMF arises as result of protons continuously pumped actively out of the cell through specialized complexes, diffusing both on the membrane and in the bulk, and finally being consumed by complexes (like the BFM) that harness their energy when falling along the potential.
Despite its importance, because of technical challenges, the dynamical properties of the PMF at the level the individual cells remain unknown.

In this project, our consortium will employ novel single-molecule manipulation and detection techniques, genetic and biochemical strategies, and develop novel theoretical analysis to better understand the dynamical character of both of the flagellar motor and its energy source, at the level of the single complex and single cell. A better understanding of the BFM dynamics will help in better understanding of the PMF, and vice versa.
This will advance our knowledge of the functioning of complex biological machines, together with shading light on the electrical activity of bacteria, fundamental knowledge with several possible repercussions in applications.