FIG 5.
Comparison of CAR binding in the substrate-binding pocket of WT CARDO (Oxy) and the Q282Y derivative of Oxy (PDB accession no. 2DE7 and 4NBH, respectively). Overlays of chains B and C of the Q282Y derivative (cyan) and WT Oxy (white) are shown in panels a and b, respectively. The Q282Y derivative and WT Oxy with bound CAR (PDB accession no. 2DE7) were superimposed with C-α. The CAR molecules are in the orientations observed in the Q282Y derivative and WT Oxy (green and yellow, respectively). The electron density (0.5 σ 2Fo-Fc) of CAR in the Q282Y derivative is shown as a black wire mesh. The water molecules that hydrogen bond with Gly178 and CAR are shown as red spheres (Wat490 and Wat448 for chains B and C, respectively). The distances between the carbonyl oxygen of Gly178 and the imino nitrogen and water molecules are also shown (insets). (c) The rotation of CAR in the substrate-binding pocket in WT Oxy and the I262V and Q282Y derivatives is shown. All of the structures, the I262V, F275W, and Q282Y derivatives and WT Oxy, complexed with CAR (PDB accession no. 4NBA, 4NBD, 4NBH, and 2DE7, respectively) are superimposed with C-α. CAR is shown in the substrate-binding pockets of the I262V (pink), F275W (blue), and Q282Y (chains B and C are in salmon and green, respectively) derivatives and WT Oxy (yellow). (d) Modeled oxygen species in the CAR-bound Q282Y derivative and the distances between carbon atoms C-1, C-2, and C-9 of CAR and the oxygen species. The oxygen species were modeled on the basis of WT Oxy complexed with CAR and oxygen species (3VMI) (26).