CRYSTALLIZATION OF THE GLYCYL-TRANSFER-RNA SYNTHETASE FROM THERMUS-THERMOPHILUS AND INITIAL CRYSTALLOGRAPHIC DATA

The glycyl-tRNA synthetase from Thermus thermophilus is a dimer of mol ecular mass 115 kDa, which has been crystallised using the vapour diff usion method from 5 to 7% polyethylene glycol 6000, 0.8 to 1.4 M NaCl at protein concentrations of 2 to 8 mg/ml. Nucleation is carried out a t 4 degrees C and crystals are subsequently transferred to 15 degrees C to maximise growth. Crystals are truncated rhombohedra, measuring on average 0.4 mm x 0.4 mm x 0.2 mm, which appear within a few days and reach full size in one to two months. GlyRS crystallises in two closel y related space groups, P2(1)2(1)2(1) and C2,2,2(1), both with the sam e cell a 125 Angstrom, b = 254 Angstrom, c = 104 Angstrom. Crystal pac king in P2(1)2(1)2(1) is strongly C-centred. The crystals have V-M = 3 .6 Angstrom(3)/Da and a solvent content of 61%, with one dimer in the asymmetric unit in C2,2,2(1) and two dimers in P2(1)2(1)2(1). The best native data extend to 2.9 Angstrom in C2,2,2(1) and are 90.6% complet e with an R-factor between symmetry-related reflections of 10.0%. The structure has been solved by multiple isomorphous replacement and mode l building is in progress.