Fig. 4
Crystal structure of the T264A HK853cp-BeF3 –-RR468 complex reveals an “apo” chemical environment for the F2 fluorine of BeF3 –-RR468. a Side view of the active site of the T264A HK853cp-BeF3 –-RR468 complex overlaid with that of the wild-type complex crystallized at pH 5.0. In the T264A complex, the BeF3 –-RR468 substrate is shown in green and the T264A HK853cp in pale purple, with the sidechains of H260 and A264 of T264A HK853cp in the stick model. In the wild-type complex, the BeF3 –-RR468 substrate is shown in cyan and HK853cp in pink, with the sidechains of H260 and T264 of HK853cp shown in the stick model. The interaction between the F2 atom of BeF3 –-D53 and the hydroxyl group of T264, bridged by the proposed catalytic water molecule (shown in the sphere model) in the wild-type complex at low pH generates the F2 ci state. The loss of the catalytic water and its bridged interactions between the F2 atom of BeF3 –-RR468 and T264 and H260 in the T264A HK853cp mutant generates a chemical environment similar to the F2 apo state. b Top view of the active site of the T264A HK853cp-BeF3 –-RR468 complex overlaid with that of the wild-type complex crystallized at pH 5.0. Interactions of the fluorine atoms in a and b are indicated by dashed lines
