Fig. 1

Representative structures of the heme-binding ferredoxin α + β barrel superfamily. (a) Ribbon diagram of the structures of OxdA (PDB identifier 3A16), Cld (PDB identifier 3NN1), MhuD (PDB identifier 3HX9), IsdG (PDB identifier 2ZDP), DyP (PDB identifier 3VXJ) and Siroheme decarboxylase (PDB identifier 4UN1). The individual ferredoxin-like folds in all structures have been colored from their N- to C-termini in chainbow coloring scheme of PyMOL and are faded to highlight the position of heme (magenta). Elements that do not constitute a part of the core of the ferredoxin-like fold are colored white. (b) A comparison of heme binding sites using topology diagrams. (c) Orientation of heme-moieties in different proteins of the ferredoxin α + β barrel superfamily. Here, the porphyrin ring of heme and siroheme substituents is shown as a rectangle and the extensions from the rectangle denote the propionate side chains