Figure 13.

HS-AFM imaging of α₃β₃ subcomplex of F₁-ATPase under different nucleotide states. (a) Crystal structure of α₃β₃γ subcomplex. The α-, β-, and γ-subunits are shown in cyan, pink, and yellow, respectively. (b) Typical HS-AFM image of α₃β₃ subcomplex immobilized on a chemically treated mica surface without nucleotide (150 × 150 pixels; imaging rate 1 fps). (c) Filtered HS-AFM image of C-terminal side of the α₃β₃ subcomplex without nucleotide. (d) C-terminal side of crystal structure of the nucleotide-free α₃β₃ subcomplex. The α and β subunits are colored in cyan and pink, respectively. The C-terminal DELSEED motif of the β subunits corresponding to the high protruding portions is highlighted in red. (e) Simulated AFM image constructed from the structure in (d). (f) Filtered AFM image of the N-terminal side of the α₃β₃ subcomplex without nucleotides. (g) N-terminal side of the crystal structure of the α₃β₃ subcomplex. (h) Simulated AFM image constructed from the structure in (g). (i) Filtered AFM image of the C-terminal side of the α₃β₃ subcomplex at 1 mM AMP-PNP. (j) Crystal structure of the α₃β₃ subcomplex with bound nucleotides. This structure is obtained by removing γ from the crystal structure of α₃β₃γ subcomplex. (k) Simulated AFM image constructed from the structure in (j).