RAD10, AN EXCISION REPAIR GENE OF SACCHAROMYCES-CEREVISIAE, IS INVOLVED IN THE RAD1 PATHWAY OF MITOTIC RECOMBINATION

The RAD10 gene of Saccharomyces cerevisiae is required for the incision step of excision repair of UV-damaged DNA. We show that the RAD10 gene is also required for mitotic recombination. The rad10Δ mutation lowered the rate of intrachromosomal recombination of a his3 duplication in which one his3 allele has a deletion at the 3′ end and the other his3 allele has a deletion at the 5′ end (his3Δ3′ his3Δ5′). The rate of formation of HIS3+ recombinants in the rad10Δ mutant was not affected by the rad1Δ mutation but decreased synergistically in the presence of the rad10Δ mutation in combination with the rad52Δ mutation. These observations indicate that the RAD1 and RAD10 genes function together in a mitotic recombination pathway that is distinct from the RAD52 recombination pathway. The rad10Δ mutation also lowered the efficiency of integration of linear DNA molecules and circular plasmids into homologous genomic sequences. We suggest that the RAD1 and RAD10 gene products act in recombination after the formation of the recombinogenic substrate. The rad1Δ and rad10Δ mutations did not affect meiotic intrachromosomal recombination of the his3Δ3′ his3Δ5′ duplication or mitotic and meiotic recombination of ade2 heteroalleles located on homologous chromosomes.