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BP: Fachverband Biologische Physik

BP 36: Cell Mechanics II

BP 36.0: Hauptvortrag

Freitag, 22. März 2024, 09:30–10:00, H 0112

Proton:ion antiporters generate membrane potential, and thus proton motive force in E.coli — •Teuta Pilizota — Centre for Engineering Biology, University of Edinburgh, Edinburgh, UK

To stay outside of thermodynamic equilibrium, all living cells need energy. Arguably the main energy source of life is the electrochemical potential of a given ion, so-called ion motive force, with the ATP molecule being the other. Because bacteria are unicellular the energy production is tightly linked with all the other processes in the cell. For example, the electrochemical potential of a given ion is composed of two parts. The electrical potential across the membrane, which is generated by the charge accumulated at the membrane, and 'drives' all ions. But also the specific chemical concentration differences of a given ion, where the exact concentration of ions in the cell matters, particularly that of protons. Lastly, bacteria maintain significant osmotic pressures, which depend on the difference between the extracellular and intracellular concentrations of all solutes, including ions. The result is a non-trivially intertwined set of physiological variables, yet, the bacterial cell does it; it achieves the necessary homeostasis of them all. How?

To begin answering the question here I'll focus on the bacterium Escherichia coli and show how it achieves a sufficient electrical potential, and in turn the electrochemical gradient of protons. The results champion a shift of perspective in the fundamental principle driving pH regulation.

Keywords: bacteria electrophysiology; membrane potential; ion motive forces; bacterial flagellar motor; bacterial energetics