TABLE 3

Genetic interactions between rad53 and several cell division cycle mutations

StrainXrad53-11(PDY258)
A. Interaction between rad53-11 and various cdc7 alleles
Wild type (299)Viable (10 tetrads)
cdc7-1 (PDY177)Slow growth phenotype (18 tetrads)
cdc7-3 (209)Synthetic lethality/inviable (12 tetrads)
cdc7-4 (576)Viable (12 tetrads)
cdc7-7 (708)Synthetic lethality/inviable (33 tetrads)
Strain                Xrad53-31(PDY289)
B. Interaction between rad53-31 and cdc8-1
cdc8-1 (199)Viable (18 tetrads)
C. Interaction between rad53-31 and dbf4-1
dbf4-1 (PDY029)Slow growth phenotype (31, 24 tetradsa)
  • Genetic interactions between rad53 and various cell cycle mutations were tested by crossing individual strains together. The diploids were sporulated and dissected and the resulting segregants were grown at the permissive temperature of 23°. The rad53-11 and the rad53-31 alleles were marked by a pep4Δ::URA3 marker, which is located directly adjacent to the RAD53 gene. The number in parentheses indicates how many informative tetrads were dissected for each cross (except in the case of the dbf4-1 cross, see below for details). In crosses that demonstrated a synthetic lethality/inviable phenotype, no viable double mutants were detected. In addition, no significant deviation from the 1PD:4T:1NPD ratio was observed for all the crosses, as predicted for the segregation of two unlinked genes (except for dbf4-1, see below). An extremely slow growth phenotype was detected in tetrad segregants from the cdc7-1 cross. Upon restreaking, double mutants from the cdc7-1 cross grew very poorly.

  • a For the dbf4-1 cross, double mutants could be obtained; however, results were complicated by the fact that out of the original 31 tetrads dissected, the dbf4-1 mutation reverted to wild type in 22 cases, generating many 3:1 and 4:0 segregation patterns for temperature resistance. To prove that double mutants were viable, this diploid was then transformed with the pRS425-DBF4 to cover the dbf4-1 mutation, 24 tetrads were dissected, and plasmids were allowed to be lost from the tetrad segregants. In this case, dbf4-1 rad53-31 double mutants were easily obtained, and dbf4-1 always segregated 2:2.