RRM3, a helicase that functions to remove non-histone protein barriers from DNA, also affects rDNA recombination [60]–[61]. Further evidence comes from a screen for deletion mutants that increase LOH in young cells [17], which classified mutations based on locus specificity, magnitude and ratio of reciprocal/non-reciprocal events. The group of deletion mutants that showed a bias toward increasing LOH at MET15 on chromosome XII (and presumably originate in the rDNA) included five genes implicated in the regulation of nucleotide pools, which can be a source of DNA replication stress [62].
