Crystallization and preliminary X-ray diffraction study of mammalian mitochondrial seryl-tRNA synthetase.

The mitochondrial seryl-tRNA synthetase (mt SerRS) from Bos taurus was overexpressed in Escherichia coli and crystallized using the sitting-drop vapour-diffusion method. Crystals grew in a very narrow range of conditions using PEG 8000 as precipitant at room temperature. An appropriate concentration of lithium sulfate was critical for crystal nucleation. Crystals diffracted well beyond a resolution of 1.6 A and were found to belong to the orthorhombic space group C222(1), with unit-cell parameters a = 79.89, b = 230.42, c = 135.60 A. There is one dimer (M(r) approximately 113 kDa) in the asymmetric unit, with a solvent content of 55%. Efforts to solve the phase problem by molecular replacement are under way.