Crystallization and preliminary X-ray diffraction analysis of the homodimeric form α₂ of the HU protein from Escherichia coli

The homodimeric form α₂ of the Escherichia coli DNA-binding protein HU was crystallized by the hanging-drop vapour-diffusion method using PEG 4000 as a precipitant. The crystals belong to space group I222, with unit-cell parameters a = 31.09, b = 55.34, c = 117.63 Å, and contain one monomer per asymmetric unit. A full diffraction data set was collected to 2.3 Å resolution on a conventional X-ray source. The molecular-replacement method, using the HU crystallographic model from Bacillus stearothermophilus as a starting point, gave a reliable solution for the rotation and translation functions.