Preliminary X-ray diffraction studies on asparaginyl-tRNA synthetase from Thermus thermophilus

The recombinant asparginyl-tRNA synthetase from the thermophilic bacterium Thermus thermophilus expressed in Escherichia coli has been crystallized from PEG 6000 solutions. Depending on the PEG concentrations the crystals were in either tetragonal or hexagonal space groups. Although generally smaller, the latter (space group P6₄22) diffracted better, to a resolution of 2.8 Å. Using the coordinates of the yeast aspartyl-tRNA synthetase structure molecular replacement methods were applied to both tetragonal and hexagonal crystals; a solution was found which gave excellent crystal packing in both space groups.