Figure 3. Inhibition of ATP hydrolysis by subunit ε.

(A) Comparison of β_DP (blue) with β_E (pink, top) and β_TP (light purple, bottom). β_DP is forced to adopt an open conformation by subunit ε (dashed box). (B) Comparison of subunits γ (pink) and ε (blue) of ATP synthases from Bacillus PS3 (top) and E. coli (bottom, PDB 3OAA (Cingolani and Duncan, 2011)). The dashed box shows additional interaction between subunits ε and γ in the E. coli complex. (C) Cross-section through the catalytic F₁ region of the Bacillus PS3 ATP synthase. Subunit ε (pink) in the rotor is blocked from rotating in the direction of ATP hydrolysis (clockwise) by β_TP but is free to rotate in the direction of ATP synthesis (counterclockwise).