Structure of the ADP complex of the 3-phosphoglycerate kinase from Bacillus stearothermophilus at 1.65 Å

The structure of the ADP complex of the enzyme 3-phosphoglycerate kinase (PGK, E.C. 2.7.2.3) from Bacillus stearothermophilus NCA-1503 has been determined by the method of molecular replacement. The structure has been refined to an R factor of 0.16 for all data between 10.0 and 1.65 Å resolution, using data collected on the Hendrix-Lentfer imaging plate at the EMBL outstation in Hamburg. The r.m.s. deviations from stereochemical ideality are 0.010 and 0.011 Å for bonds and planes, respectively. Although crystallized in the presence of the nucleotide product MgATP, the high-resolution structure reveals the bound nucleotide to be MgADP reflecting the low intrinsic ATPase activity of PGK. Although the two domains of this enzyme are found to be some 4.5° closer together than is found in the yeast and horse-muscle apo-enzyme structures, this structure represents the `open' rather than the `closed', catalytically competent form, of the enzyme.