Figure 3.

Crystallographic structures depicting the rotation of the hydroxymethyl group [45]. (a) The IspH WT was incubated with the substrate HMBPP. The full iron-sulfur cluster is present and the CH₂OH group is coordinated to the apical iron, stabilized by T167. (b) The IspH T167C mutant was incubated with the substrate HMBPP. The CH₂OH group has rotated about almost 180° and is now stabilized by the diphosphate group as well as the glutamate E126. The crystal structure only shows a [3Fe-4S] cluster.