Crystallization and preliminary X-ray diffraction studies of glycerol 3-phosphate cytidylyltransferase from Staphylococcus aureus

Glycerol 3-phosphate cytidylyltransferase from Staphylococcus aureus (TarD( Sa)) has been expressed in Escherichia coli, purified to homogeneity and cr ystallized. The strategy used for determining crystallization conditions em ployed hanging-drop sparse-matrix screens and required a combination of thr ee different optimization approaches. Specifically, the presence or absence of cofactors needed to be surveyed, the effects of small-molecule additive s required exploration and the rate of vapour-diffusion had to be varied in order to obtain crystals of TarD(Sa) suitable for diffraction studies. Cry stals thus obtained belong to the space group P3(1)21, with unit-cell param eters a = b = 92.2, c = 156.1 Angstrom, and contain four TarD(Sa) molecules per asymmetric unit. The resolution limit observed for these crystals usin g synchrotron radiation is 3.0 Angstrom.