Crystallization and Preliminary X-ray Diffraction Study of Phosphoribosyl Pyrophosphate Synthetase from E-Coli

Enzymes of the phosphoribosyl pyrophosphate synthetase family (PRPPS, EC 2.7.6.1) catalyze the formation of 5-phosphoribosyl pyrophosphate (5-PRPP) from adenosine triphosphate and ribose 5-phosphate. 5-Phosphoribosyl pyrophosphate is an important intermediate in the synthesis of purine, pyrimidine, and pyridine nucleotides, as well as of the amino acids histidine and tryptophan. The crystallization conditions for E. coli PRPPS were found by the vapor-diffusion technique and were optimized to apply the capillary counter-diffusion technique. The X-ray diffraction data set was collected from the crystals grown by the counter-diffusion technique using a synchrotron radiation source to 3.1-angstrom resolution. The crystals of PRPPS belong to sp. gr. P6(3)22 and have the following unit-cell parameters: a = b = 104.44 angstrom, c = 124.98 angstrom , alpha = beta = 90 degrees, gamma = 120 degrees. The collected X-ray diffraction data set is suitable for the solution of the three-dimensional structure of PRPPS at 3.1-angstrom resolution.