FIGURE 6:

nse1-C216S requires the error-free branch of PRR to suppress the MMS DNA damage sensitivity of smc6-74. All strains were constructed by tetrad dissection and confirmed by backcrossing. MMS and UV sensitivity assays were performed as described in the previous figures. (A) rhp18Δ increases the sensitivity of smc6-74 to MMS (A) but not to UV (B), and nse1-C216S cannot suppress this at MMS concentrations of ≥ 0.003% or to all doses of UV. (C) A series of strains lacking ubc13, which encodes the ubiquitin-conjugating enzyme required for error-free PRR, were constructed. These were tested for MMS sensitivity using spots of 10-fold serial dilutions, with plates incubated at 30°C for 4 d. ubc13Δ significantly enhances the sensitivity of smc6-74 to MMS, and nse1-C216S fails to suppress this at MMS concentrations of ≥ 0.003%.