Crystal structure of RecR, a member of the RecFOR DNA-repair pathway, fromPseudomonas aeruginosaPAO1

Abstract

DNA damage is usually lethal to all organisms. Homologous recombination plays an important role in the DNA damage-repair process in prokaryotic organisms. Two pathways are responsible for homologous recombination inPseudomonas aeruginosa: the RecBCD pathway and the RecFOR pathway. RecR is an important regulator in the RecFOR homologous recombination pathway inP. aeruginosa. It forms complexes with RecF and RecO that can facilitate the loading of RecA onto ssDNA in the RecFOR pathway. Here, the crystal structure of RecR fromP. aeruginosaPAO1 (PaRecR) is reported.PaRecR crystallizes in space groupP6122, with two monomers per asymmetric unit. Analytical ultracentrifugation data show thatPaRecR forms a stable dimer, but can exist as a tetramer in solution. The crystal structure shows that dimericPaRecR forms a ring-like tetramer architectureviacrystal symmetry. The presence of a ligand in the Walker B motif of one RecR subunit suggests a putative nucleotide-binding site.