FIGURE 4.

The conformational changes of Tom71 generated by Hsp70 binding. a, the N-terminal domain of Tom71 is superimposed with that in the Tom71-Hsp70 complex and they are shown by a ribbon drawing. The Tom71 N-terminal domain is in light blue. The Tom71 N-terminal domain within the Tom71-Hsp70 complex is in silver. The bound Hsp70 C-terminal peptide is in red. Helices A5, A6, and A7 are labeled in blue. Some residues of Tom71 involved in generating the conformational changes are labeled in black. Residues Lys¹⁹⁶, Arg²⁰⁰, and Leu¹⁹⁹ of Tom71 involved in binding Hsp70 are labeled. The residues forming hydrophobic cluster to associate A5, A6, and A7 are labeled. Glu²⁰⁶ and Arg²³⁸ linking A5 and A7 by forming a salt bridge are also labeled. b, Cα trace drawings of yeast Tom71 structure and the Tom71-Hsp70 complex structure. The N-terminal domain of Tom71 is superimposed with that in the Tom71-Hsp70 complex structure. The molecules in this figure are in a similar orientation as in a. The uncomplexed Tom71 structure is in purple. In the Tom71-Hsp70 C terminus complex, Tom71 is in green, and the Hsp70 C terminus is in red. The N- and C-terminal domains of Tom71 are labeled. Helix A7 acting as the hinge to connect the N-and C-terminal domains of Tom71 is labeled.