Production, biophysical characterization and crystallization ofPseudomonas putidaGraA and its complexes with GraT and thegraTAoperator
ThegraTAoperon fromPseudomonas putidaencodes a toxin–antitoxin module with an unusually moderate toxin. Here, the production, SAXS analysis and crystallization of the antitoxin GraA, the GraTA complex and the complex of GraA with a 33 bp operator fragment are reported. GraA forms a homodimer in solution and crystallizes in space groupP21, with unit-cell parametersa= 66.9,b = 48.9,c= 62.7 Å, β = 92.6°. The crystals are likely to contain two GraA dimers in the asymmetric unit and diffract to 1.9 Å resolution. The GraTA complex forms a heterotetramer in solution. Crystals of the GraTA complex diffracted to 2.2 Å resolution and are most likely to contain a single heterotetrameric GraTA complex in the asymmetric unit. They belong to space groupP41orP43, with unit-cell parametersa=b= 56.0,c= 128.2 Å. The GraA–operator complex consists of a 33 bp operator region that binds two GraA dimers. It crystallizes in space groupP31orP32, with unit-cell parametersa=b= 105.6,c= 149.9 Å. These crystals diffract to 3.8 Å resolution.