Crystal structure (PDB:5ZDR) of the alternative oxidase (AOX) dimer.
(A and B) Surface model of the dimer showing hydrophobic residues in orange, hydrophilic in grey. (B) shows the entrance to the hydrophobic cavity in the membrane associating side of the protein, with the inhibitor depicted as green sticks and a leucine ‘gate', which controls inhibitor orientation, colored blue. (C) Helical structure of the dimer in the same orientation as A, with monomers colored magenta and yellow, respectively. Inhibitor can be seen as green sticks to show position of the hydrophobic cavity between helices 1 and 4 leading directly to the di-iron core, which shown as orange spheres. (D) The binding pocket within the protein, showing all amino acids within 5 Å of the inhibitor. Key hydrogen bonding between the phenol, Arg-118 and Thr-219 shown as yellow dotted line (inlet).