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 A, b = 97.3 A, c = 62.1 A, alpha = 108.3 degrees, beta = 97.4 degrees and gamma = 90.0 degrees. Diffraction from this form extends beyond 3 A resolution, but the crystals are radiation-sensitive and difficult to reproduce. Form II has the unit cell dimensions a = 62.6 A, b = 72.2 A, c = 58.5 A, alpha = 99.1 degrees, beta = 101.5 degrees and gamma = 72.0 degrees; most likely, the unit cell contains two molecules. High diffraction quality and reproducibility make form II suitable for structure analysis.