Expression, purification, crystallization and preliminary X-ray diffraction analysis of human phosphoribosyl pyrophosphate synthetase 1 (PRS1)

Abstract

Phosphoribosyl pyrophosphate synthetase (PRS; EC 2.7.6.1) catalyzes the reaction of ribose-5-phosphate (R5P) with ATP to yield AMP and PRPP (5-phosphoribosyl-1-pyrophosphate), which is necessary for the de novo and salvage pathways of purine-, pyrimidine- and pyridine-nucleotide biosynthesis. PRPP is a metabolite that is required at all times in the cell and is thus central to life. In this study, human PRS1 was produced in Escherichia coli in soluble form and purified to homogeneity. Crystals in complex with Mg2+, inorganic phosphate (P(i)) and ATP were obtained by the hanging-drop vapour-diffusion method. Diffraction data were collected to 2.6 A resolution. The crystal belongs to space group R3, with unit-cell parameters a = b = 168.846, c = 61.857 angstroms, assuming two molecules in the asymmetric unit and a volume-to-weight ratio of 2.4 angstroms3 Da(-1), which was consistent with the result calculated from the self-rotation function.

Figure 1

SDS–PAGE of PRS1 under non-reducing condition. Lane 1, purified fraction from Ni–NTA column (more than 95% purity); lane M, molecular-weight markers (kDa).

Figure 2

Crystals of PRS1 in complex with ATP, Mg²⁺ and P_i grown by the hanging-drop method.