Figure 1.

ATP-synthase c-ring motion monitored by HS-AFM (full false color scale: 35 Å). (A) Two c-rings in a dimer over a time span of 1309 ms (of a longer movie), swinging of the c-rings in the dimer is observed. (B) The c-ring dimer that dissociates and reforms. Intermediately one c-ring is monomeric for ∼400 ms (frames: 561 ms, 748 ms, 935 ms) and subsequently reforms a dimer that resembles the initial assembly. (C) Three examples of ATP-synthase c-ring assemblies. (Left to right) Close dimer (center-to-center distance 80 Å); elongated dimer (center-to-center distance 120 Å); and monomer. (D) Real-space representation of particle tracking. (Black dots and lines) The c-ring remaining in the frame. (Red and blue dots and lines) Trajectories of alternating c-rings. (E) Mean-square displacement for monomer (solid triangles) and dimer (open circles) c-rings fitted as described (see Section 5 in the Supporting Material). The obtained exponent values (±SD) were α = 1.0 ± 0.9 in the case of monomers, and α = 0.2 ± 0.1 for the dimer configuration. These results indicated diffusive and subdiffusive motion of the monomer and dimer, respectively.