Figure 1.

(A) Stereo cartoon representation of subunit ɛ (dark gray) in an extended conformation. Partly shown are subunit γ (white) and subunit β proximal to the C-terminal domain of ɛ. Fluorescent labels are shown as large colored spheres (magenta: Cy3 on the N-terminus of γ; blue: Cy5 on the C-terminus of ɛ). Residues mutated to reduce the affinity of subunit ɛ to ATP are shown as small orange spheres, and the βDELSDED region is shown in green. The figure was generated from Protein Data Bank entry 1JNV of the E. coli α₃β₃γɛ complex (40) with VMD software (53). (B) Cartoon scheme of subunit ɛ conformational transitions in Bacillus PS3 F_OF₁ ATP synthase. Subunit γ is shown in white, subunit ɛ in dark gray, and α₃β₃δ-complex and F_O in light gray. Positions of introduced Cy3 on subunit γ and Cy5 on subunit ɛ are indicated by a magenta and blue star, respectively. See details at the end of the Discussion.