Cocrystallization of Lysyl–tRNA synthetase from Thermus thermophilus with its cognate tRNAlys and with Escherichia coli tRNAlys

Lysyl-tRNA synthetase from Thermus thermophilus has been cocrystallized with either its cognate tRNAlys or Escherichia coli tRNAlys using ammonium sulfate as precipitant. The crystals grow from solutions containing a 1:2.5 stoichiometry of synthetase dimer to tRNA in 18-22% ammonium sulfate in 50 mM Tris-maleate buffer at pH 7.5. Both complexes form square prismatic, tetragonal crystals with very similar unit cell parameters (a = b = 233 A, c = 119 A) and diffract to at least 2.7 A resolution. However the homocomplex is of space group P42(1)2 and the heterocomplex of space group I422.