Figure 8

Overlays of the H. volcanii MSH active sites with the corresponding E. coli MSG complexes. Overlays were performed by superimposing glyoxylate molecules in part a, or pyruvate molecules in part b, using LSQ in Coot. Residue numbers refer to the H. volcanii sequence. Side chains at positions 190 and 191, and at corresponding positions in ecMSG, have been omitted for clarity. a) Stereoview of high-occupancy glyoxylate complex overlay [PDB:1D8C for ecMSG]. Rendered as in figure 7a, with hvMSH carbon atoms yellow, and ecMSG carbons blue. The magnesium ion and water molecules are colored blue and red respectively in the ecMSG complex, and yellow and lilac in the hvMSH complex. All hydrogen and metal-ligand bonds are colored yellow in hvMSH, and blue in ecMSG. b) Stereoview of pyruvate/Acetyl-CoA ternary complex overlay [PDB:1P7T for ecMSG]. Rendered as in part a, but with carbons, magnesium ions, and bonding interactions in green or blue for hvMSH or ecMSG respectively. Water molecules are lilac for hvMSH and red for ecMSG. Distances are shown in angstroms to show proximity of the acetyl-CoA methyl carbon to either the catalytic base oxygen (Asp 388) or the ketone carbonyl of pyruvate.