Fig. 3: ATP/Mg²⁺ dependence of the in vitro assembly process of the full F₁ complex of Na⁺-F₁F_O- ATP synthases of A. woodii.

The α- (light blue), β-subunit (dark blue), γε-complex (dark and light green) were incubated at 4 °C for 1 h either without (a) or with (c) 2 mM ATP and 2 mM MgCl₂. Then the δ-subunit (yellow) was added (b, d). a, b No specific assemblies into higher F₁-subcomplexes could be detected without ATP/Mg²⁺. The appearance of the γ subunit alone is due to dissociation. (See as well Supplementary Fig. 8c). c, d In presence of ATP/Mg²⁺ the fully assembled F₁ can be identified with additional F₁ subcomplexes (e.g., α₂β₂γε, αβγε, αβγ) implying pairwise specific αβ heterodimer association. The δ-subunit can only bind when a complex containing the hexameric head domain α₃β₃ is already preformed. Source data are provided as a Source Data file.