Crystallization and preliminary X-ray crystallographic analyses of EcoO109I and its complex with DNA

EcoO109I is a type II restriction endonuclease that recognizes seven base pairs of the degenerate and discontinuous sequence RGGNCCY. The enzyme and its complex with DNA were successfully crystallized by the hanging-drop vapour-diffusion method using polyethylene glycols as precipitants. The crystal of EcoO109I belongs to space group I4, with unit-cell parameters a = b = 175.5, c = 44.6 Å, and that of the DNA complex belongs to space group P2₁2₁2₁, with unit-cell parameters a = 49.1, b = 71.8, c = 203.2 Å. Full sets of X-ray diffraction data from the enzyme and its complex with DNA were collected to 2.4 and 1.9 Å resolution, respectively.