Long-Range Residue Interaction Mecahnism Induced By F186L Mutation Affecting The Active Site Of CYP1A2

CYP1A2, one of the major members of cytochrome P450 in human liver, can metabolize phenacetin efficiently. Whereas, an experimental study revealed that F186 L mutation, a peripheral residue distant from the active site, in CYP1A2 significantly reduced its phenacetin O-deethylation activity. In this paper, ensemble docking and MD simulation were employed to illustrate the long-range residue interaction mechanism induced by the F186 L mutation inhibiting the enzyme activity of CYP1A2. The mechanism was as follows: F186 L mutation had lowered interaction energy with the other residues, resulting in higher flexibility of this region. So, Y189 formed hydrogen bond with D320, making part of D helix?E helix and D-E loop move towards the “interior” of CYP1A2 and D320 move towards the opposite direction. Then the movement of D320 made the carbon terminal of F helix slide towards the “upper left” of CYP1A2, which made F226 on it also slide towards this direction. So, phenacetin subsequently rotated from the “lying state” to the “upright” due to the ?-? stacking with F226. The rotation of phenacetin, on the one hand, made B' helix/B-C loop move towards the “interior” of CYP1A2 and, on the other hand, made the residues in the active site of the protein rearranged. Among which, F260 and F319 rotated about 90 degrees making G helix move towards the “interior” of CYP1A2 slightly, and some gating residues of the channels rotated making the S channel and the 2f channel transiently closed, the 2c channel relatively open and the 2e channel relatively closed. As a result, a good number of water molecules were retained in the active site of CYP1A2 and the exit of product was interfered. Thus the enzyme activity was greatly decreased. This study observed the alternate open-closed states of the main channels of CYP1A2 and firstly illustrated the open-close mechanism of these channels, and the long-range residue interaction mechanism between the F186 L mutation and the active site of CYP1A2, which might offer some theoretical ideas for the structure-based rational drug design for CYP1A2 or other cytochrome P450 enzymes.