Characterization of the effect of smt3-I96R mutation on cell growth, accumulation of GCRs and intracellular sumoylation.

(A) Plate assay showed that smt3-I96R mutation does not cause any appreciable growth defect in the presence of genotoxic agents. The mec1Δ mutant is used as a positive control for its hypersensitivity to genotoxic agents including hydroxyurea (HU), camptothecin (CPT) and UV radiation. (B) Rates of accumulating GCRs in smt3-I96R mutant (strain HZY4247) and smt3GG mutant (strain HZY3392), both containing a C-terminal stop codon to expose the Gly-Gly repeat and thus mature SUMO in cells. (C) Abundance ratios of the purified sumoylated proteins in WT (HZY2101) and smt3-I96R (HZY4248) strains, measured by quantitative MS using the method described previously [16].