Figure 2

Active site of NM-IIA^Ntr. (a) Stereo figure of an overlay of the active sites of NM-IIA^Ntr (green line for main chain and orange for side-chains displayed as ball-and stick) and E. coli IIA^mtl (grey line for main chain and individual side-chains) showing the positions of residues around the active site H67 and the sulphate ions observed in the structures of both NM-IIA^Ntr and E. coli IIA^Ntr [9]. Residues are numbered according to the sequence of NM-IIA^Ntr. Hydrogen bonds are shown by broken yellow lines and nitrogen, oxygen and sulphur atoms are displayed as blue, red and yellow respectively. (b) Stereo figure of an overlay of NM-IIA^Ntr (red for the main chain ribbon and green for interface residues displayed as ball-and-stick) and E. coli IIA^mtl (grey for the main chain and orange for interface residues) showing the relative positions of the residues which form the interface between E. coli IIA^mtl HPr and the corresponding residues in NM-IIA^Ntr. Residues are numbered according to the sequence of NM-IIA^Ntr