Crystals of Thermus thermophilus tRNA (Asp) complexed with its cognate aspartyl-tRNA synthetase have a solvent content of 75%. Comparison with other aminoacylation systems

Thermus thermophilus tRNA(Asp), purified from a nonrecombinant source, has been crystallized ina-complex with its cognate dimeric (alpha 2) aspartyl-t RNA synthetase. Crystals diffract to 2.9 Angstrom resolution and belong to space group P6(3) with cell parameters a = b = 258, c = 90.9 Angstrom. The crystals contain one aspartyl-tRNA synthetase dimer and two tRNA molecules in the asymmetric unit, corresponding to a V-m of 4.85 Angstrom Da(-1) and 75% solvent content, When compared with those obtained for globular protein s these values are high, but fall within the range observed for other amino acyl-tRNA Synthetases, either free or complexed with their tRNAs. A compara tive survey is presented here.