Figure 1. Crystal structures of NrfB.

All Figures showing protein structures were prepared using PyMOL (DeLano Scientific). (A) The crystal structure of E. coli NrfB represented as the α-carbon trace with five haems and Trp¹⁰² displayed in green. (B) Haem organization within NrfB, histidine side chains are shown in blue. The distances (in Å) between haems are shown above; the haem numbers are shown underneath. (C) Superimposition of the oxidized and reduced haem structures. The α-carbon trace and haems of the oxidized and reduced enzymes are shown in red and blue respectively. (D) Superimposition of haems 1, 2 and 3 (blue) over haems 3, 4 and 5 (green) with an rmsd of 1.9 Å. The haem numbering refers to the green haems. (E) Region of the electron-density map contoured at 1.1 σ calculated from the final refined structure of oxidized NrfB in the region of haems 5, 4 and 3 and Trp¹⁰². The Figure demonstrates the quality of the fit of the structural model to the map.