Figure 5.

Enzymes with FMN-binding domains. Proteins from the PNPOx-like subfamily contain a β-barrel with a Greek key topology (a protein structure consisting of four antiparallel strands connected by three hairpin loops that is named for a common pattern in Grecian decoration). The pictured enzymes also contain FMN-binding domains, although neither HutZ or HupZ can bind FMN. (A) (from left to right) a monomer of HugZ and a monomer of ChuZ. In both representations, the PNPOx domain is in white. In ChuZ, the canonical heme binding pocket is indicated by the orange arrow. (B) (from left to right) HutZ and HupZ. In both representations one monomer is colored blue and the other monomer is colored teal.