Illustration of RuvC, a Holliday junction resolvase from the bacterium Thermus thermophilus, in complex with a synthetic DNA (deoxyribonucleic acid, orange) molecule. A Holliday junction forms during crossing over, a natural genetic process that occurs between homologous chromosomes and leads to the switching of genetic material between the chromosomes. This recombination increases the genetic variation in a population. RuvC is part of the RuvABC complex of three proteins that mediate branch migration and resolve the Holliday junction created during homologous recombination in bacteria. RuvC cleaves the DNA strands to end the Holliday junction.