Protons on a Spin: The Proton Motive Force Powers Bacteria’s Tiny Engine

The article describes how bacteria run on a proton motive force that powers the flagellar motor, a nanoscale engine at the base of the flagellum. Recent cryo-EM studies mapped the motor’s components—especially the C ring and its stators—revealing how protons drive rotation and how phosphorylation of CheY flips the motor to switch between running and tumbling, illustrating how proton energetics power core cellular processes and life’s physics-driven machinery.