Fig. 2

Biological assembly and comparison to other PRPP synthetases. EcKPRS forms a propeller-shaped hexamer with 32 point symmetry (a). The location of the active sites is marked by an AMP molecule (shown in space-filling representation; the AMP is from superposition of the EcKPRS structure with that of 3DAH). Note that the protomer colored with blue helices and green strands is in the same orientation as that shown in Fig. 1. b The PRPP synthetase from B. subtilis (1DKR, green; 0.92 Å RMSD from EcKPRS) and human (2H06, yellow; 0.94 Å RMSD from EcKPRS) superimpose well with the EcKPRS protomer (blue). Comparison of some of the conserved residues (c) shows only subtle differences in side chain positions in the active site (EcKPRS shown with green carbon atoms, human PRPP synthetase shown with purple carbon atoms, B. subtilis PRPP synthetase shown with orange carbon atoms and the B. pseudomallei PRPP synthetase is shown with yellow carbon atoms). For reference, the AMP molecule from the B. pseudomallei structure (3DAH) is shown in grey