Figure 7. Histone E3 ligase mutants exhibit varying degrees of sensitivity to the replication inhibitor hydroxyurea.

(A) hel1, hel2 and pep5 mutants are sensitive to hydroxyurea. 10-fold serial dilutions of the indicated strains were plated on media containing glucose with or without the indicated concentrations of hydroxyurea (HU) and incubated at 30°C for 3 days before being photographed. (B) Mutations in the RING finger domains of Hel1 and Hel2 render them sensitive to HU. 10-fold serial dilutions of the indicated strains were plated on media containing galactose with or without 200 mM HU and incubated at 30°C for 3 days before being photographed. The hel1-r₁r₂ mutant carries inactivating mutations in both r finger domains of Hel1, while the hel2-r mutant carries inactivating mutations in the single r finger domain of Hel2. The rad53 deletion strain was included as a positive control.