Figure 4.

Sumoylation has a negative effect on transcription of inducible genes. (A, B) Occupancy of SUMO (left) and RNAP II (middle) was determined in uninduced and induced conditions (indicated; as in Fig. 3A) for STL1 (A) and ARG1 (B) in ubc9-1 cells (black bars) and isogenic wild-type cells (gray bars). (Right) Steady-state STL1 (A) and ARG1 (B) mRNA abundance in wild-type and ubc9-1 cells was determined by RT–PCR in untreated or induced cells, as indicated. Values are shown relative to transcript abundance in wild-type cells after induction, which is set to 100. Statistical analysis indicates that RNAP II levels are significantly different in the wild-type and ubc9-1 data sets (P < 0.03 for STL1 data, and P < 0.008 for ARG1 data). RNA levels were also significantly different in wild-type and ubc9-1 cells, with P-values of 0.02 and 0.03 for STL1 and ARG1, respectively. (C) Growth comparison of wild-type and ubc9-1 cells in 0, 0.4, and 0.6 M NaCl in rich medium (left) or minimal medium lacking Val and Ile, and the same medium supplemented with 0.5 μg/mL SM (right). Spot assays were performed as in Figure 2B. Growth was for 2 d at 28°C.