Crystallization and preliminary X-ray characterization of the atypical glutaminyl-tRNA synthetase from Deinococcus radiodurans.

The glutaminyl-tRNA synthetase (GlnRS) from the radiation-resistant bacterium Deinococcus radiodurans differs from known GlnRSs and other tRNA synthetases by the presence of an additional C-terminal domain resembling the C-terminal region of the GatB subunit of tRNA-dependent amidotransferase (AdT). This atypical synthetase was overexpressed in Escherichia coli, purified and crystallized in the presence of PEG 3350. Orthorhombic crystals were obtained that belong to space group P2(1)2(1)2(1) and diffract to 2.3 A resolution. The crystal structure was solved by molecular replacement using the structure of E. coli GlnRS as a search model.