Structure of the GcpE (IspG)-MEcPP complex from Thermus thermophilus

► Substrate binding to GcpE involves a large domain rearrangement. ► Its structure at 1.55 Å resolution can be exploited for inhibitor design. ► The apical Fe of the [4Fe-4S] cluster is ligated to the C3 oxygen of MEcPP. ► Active site analysis provides valuable mechanistic information.