Crystallization of a member of the recFOR DNA repair pathway, RecO, with and without bound oligonucleotide

RecFOR proteins are important for DNA repair by homologous recombination in bacteria. The RecO protein from Thermus thermophilus was cloned and purified, and its binding to oligonucleotides was characterized. The protein was crystallized alone and in complex with a 14-mer oligonucleotide. Both crystal forms grow under different crystallization conditions in the same space group, P3(1)21 or P3(2)21, with almost identical unit-cell parameters. Complete data sets were collected to 2.8 and 2.5 Angstrom for RecO alone and for the RecO-oligonucleotide complex, respectively. Visual comparison of the diffraction patterns between the two crystal forms and calculation of an R-merge of 33.9% on F indicate that one of the crystal forms is indeed a complex of RecO with bound oligonucleotide.