Crystallization and preliminary X-ray diffraction analysis of the homodimeric form alpha(2) of the HU protein from Escherichia coli

The homodimeric form alpha(2) of the Escherichia coli DNA-binding protein H U was crystallized by the hanging-drop vapour-diffusion method using PEG 40 00 as a precipitant. The crystals belong to space group I222, with unit-cel l parameters a = 31.09, b = 55.34, c = 117.63 Angstrom, and contain one mon omer per asymmetric unit. A full diffraction data set was collected to 2.3 Angstrom resolution on a conventional X-ray source. The molecular-replaceme nt method, using the HU crystallographic model from Bacillus stearothermoph ilus as a starting point, gave a reliable solution for the rotation and tra nslation functions.