Purification, characterization and crystallization of thermostable anthranilate phosphoribosyltransferase from Sulfolobus solfataricus

Anthranilate phosphoribosyltransferase (TrpD; EC 2.4.2.18) from the hyperth ermophilic archaeon Sulfolobus solfataricus (ssTrpD) was expressed in Esche richia coli, purified and crystallized. Analytical gel permeation chromatog raphy revealed a homodimeric composition of the enzyme. The steady-state ki netic characteristics suggest tight binding of the substrate anthranilic ac id and efficient catalysis at the physiological growth temperature of S. so lfataricus. Crystals of ssTrpD diffract to better than 2.6 Angstrom resolut ion and preliminary X-ray characterization was carried out. The crystals ar e suitable for structure determination.