Crystallization and preliminary crystallographic analysis of Escherichia coli DNA photolyase

DNA photolyase from Escherichia coli (M_r 54,000) consists of a polypeptide chain of 471 amino acids and the non-covalently bound cofactors methenyltetrahydrofolate (MTHF) and flavin adenine dinucleotide (FADH₂). Two crystal forms of the enzyme were obtained; both have symmetry of space group P1. Form I has the unit cell dimensions a = 89.4 Å, b = 97.3 Å, c = 62.1 Å, α = 108.3°, β = 97.4° and γ = 90.0°. Diffraction from this form extends beyond 3 Å resolution, but the crystals are radiation-sensitive and difficult to reproduce. Form II has the unit cell dimensions a = 62.6 Å, b = 72.2 Å, c = 58.5 Å, α = 99.1°, β = 101.5° and γ = 72.0°; most likely, the unit cell contains two molecules. High diffraction quality and reproducibility make form II suitable for structure analysis.