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 Angstrom, and that of the DNA complex belongs to space group P2(1)2(1)2(1), with unit-cell parameters a=49.1, b=71.8, c=203.2 Angstrom. Full sets of X-ray diffraction data from the enzyme and its complex with DNA were collected to 2.4 and 1.9 Angstrom resolution, respectively.