FIG 7 .
Overexpression of Por2 suppresses the por1Δ mutant defect in transcriptional activation by LexA-Snf1-G53R. (A) Reporter strain CTY10-5d (WT) and its mutant derivatives expressing LexA-Snf1-G53R and either overexpressing Por2-V5 (+) or carrying the corresponding empty vector (−) were grown in selective SC containing high (2%) glucose to mid-log phase and then shifted for 3 h to an otherwise identical medium containing low (0.05%) glucose. β-Galactosidase activity was assayed in permeabilized cells and measured in Miller units (4 or 5 independent transformants per genotype/plasmid combination). Shown are the values under low-glucose conditions expressed as a percentage of the mean value for the wild type plus vector (347 Miller units); in high glucose, all values were <3% of this reference value. Error bars indicate standard errors. Statistical analyses were conducted using the two-tailed Student t test. Four tests were performed. The significance level was Bonferroni adjusted from α = 0.05 to αadj = 0.012. The graph shows the results for two of these tests. n.s., not significant (P = 0.071). In addition, the value for por1Δ without Por2-V5 was significantly different from that for the wild type without Por2-V5 (P = 0.009). All values for gal83Δ and gal83Δ por1Δ with or without Por2-V5 were small (<1% of the reference value for the wild type without Por2-V5); as a group, these small values were significantly different even from the next smallest value for por1Δ without Por2-V5 (P < 0.001). (B and C) Transformants were shifted to 0.05% glucose as described for panel A and tested for Thr210 phosphorylation of the Snf1-G53R moiety (PT210), total LexA-Snf1-G53R protein levels, and Por2-V5 expression by immunoblotting.