Regulation of bacterial ATP synthase activity: A gear-shifting or a pawl-ratchet mechanism?

The F1Fo-ATP synthase, a widely distributed nanomotor responsible of ATP synthesis, rotates its central rotor reversibly: In the clockwise direction when viewed from the Fo (with the observer facing the positive side of the energy transducing membrane and looking down into the negative side of the membrane), it functions as ATP synthase, while in counterclockwise sense, it operates as a proton-pumping ATP hydrolase. Regulation exerted by naturally occurring inhibitory proteins of the enzyme appears to function by avoiding ATP hydrolysis while preserving ATP synthesis. The work of Liu et al. describes an unbiased, elegant analytical pipeline that provides important insights into the inhibitory role of the epsilon-subunit of the bacterial F1Fo-ATP synthase in vivo. We discuss if a gear-shifting versus a pawl-ratchet mechanism may explain the regulatory role of the epsilon-subunit.

Automated summary

The central rotor of F1Fo-ATP synthase can rotate clockwise or counterclockwise, functioning as either ATP synthase or ATP hydrolase. The regulation by inhibitory proteins helps preserve the key function of ATP synthesis. The study highlights the inhibitory role of the epsilon subunit in bacterial F1Fo-ATP synthase.