The translesion synthesis pathway of DNA damage tolerance promotes growth in response to NAM and MMS in slx4Δ and pph3Δ mutants. (A) dot1Δ-mediated suppression of the NAM sensitivity of slx4Δ and pph3Δ mutants does not depend on the Rev3 subunit of translesion DNA polymerase Zeta. Cells were grown in 96 well plates and OD reading were assessed as described in Materials and Methods. (B) rad9Δ-mediated suppression of the NAM sensitivity of slx4Δ and pph3Δ mutants depends on PCNA K164. Cells were treated as in A. (C–D) dot1Δ- and rad9Δ-mediated rescue of the NAM sensitivity of slx4Δ and pph3Δ mutants require RAD18 but not MMS2. Cells were treated as in A. (E–F) dot1Δ-mediated rescue of the MMS sensitivity of slx4Δ and pph3Δ depends on the Rev3 subunit of translesion DNA polymerase Zeta. Cells were serially diluted, spotted on the indicated medium and incubated at 30°C. (G) Translesion synthesis promotes completion of the cell cycle, but not S phase progression, in dot1Δ, dot1Δ slx4Δ and dot1Δ pph3Δ mutants treated with MMS. Cells were synchronized in G1 with alpha factor and released in YPD containing 0.03% MMS. Samples were taken at indicated time and processed for DNA content analysis by flow cytometry. MMS: methyl methanesulfonate. 1n, 2n: DNA content.