Mechanically driven ATP synthesis by F1-ATPase

ATP, the main biological energy currency, is synthesized from ADP and inorganic phosphate by ATP synthase in an energy-requiring reaction. The F1 portion of ATP synthase, also known as F1-ATPase, functions as a rotary molecular motor: in vitro its γ-subunit rotates against the surrounding α3β3 subunits, hydrolysing ATP in three separate catalytic sites on the β-subunits. It is widely believed that reverse rotation of the γ-subunit, driven by proton flow through the associated Fo portion of ATP synthase, leads to ATP synthesis in biological systems. Here we present direct evidence for the chemical synthesis of ATP driven by mechanical energy. We attached a magnetic bead to the γ-subunit of isolated F1 on a glass surface, and rotated the bead using electrical magnets. Rotation in the appropriate direction resulted in the appearance of ATP in the medium as detected by the luciferase–luciferin reaction. This shows that a vectorial force (torque) working at one particular point on a protein machine can influence a chemical reaction occurring in physically remote catalytic sites, driving the reaction far from equilibrium.