Interaction between checkpoint genes RAD9, RAD17, RAD24, RAD53, and genes SRM5/CDC28, SRM8/NET1, and SRM12/HFI1 involved in the determination of yeast Saccharomyces cerevisiae sensitivity to ionizing radiation

Analysis of radiosensitivity of double mutants in the yeast Saccharomyces cerevisiae revealed that checkpoint genes RAD9, RAD17, RAD24, and RAD53 along with genes CDC28 and NET1 belong to one epistasis group designated the RAD9 group. The use of srm mutations allowed the demonstration of a branched RAD9-dependent pathway of cell radioresistance. Mutation cdc28-srm is hypostatic to rad9Δ, rad17Δ, and rad24Δ being additive with rad53. Mutation net1-srm is hypostatic to rad9Δ and rad53 but additively enhance the effects of mutations rad17Δ and rad24Δ. Gene SRM12/HFI1 is not a member of the RAD9 group. Mutation in gene hfi1-srm manifests the additive effect on mutations rad24Δ and rad9Δ. The analyzed genes can also participate in minor mechanisms of radioresistance that are relatively independent of the above RAD9-dependent mechanism.