FIG 6.

Transcript stability is influenced by the activator, not the transition from respiration to fermentation. (A) Strain CKY27 (adr1Δ snf1Δ) carrying the chimeric gene ADR1-EV on the centromeric plasmid pRR01 was grown in synthetic medium lacking histidine but with 5% glucose to an A₆₀₀ of ∼1. Different portions of the culture were maintained under repressing conditions or subjected to derepression, in each case with or without induction with 1 nM β-estradiol. The data represent the average results and standard deviations from three replicate experiments. (B) β-Estradiol induction of gene expression requires the chimeric Adr1-EV activator. Cultures of strain CKY27 (adr1Δ snf1Δ) carrying the chimeric gene ADR1-EV on pRR01 (ADR1-EV), a WT ADR1 gene carried on pKD16H (WT), or pRS313, a HIS3 vector with no ADR1 (vector [V]), were grown to mid-log phase in SC medium without histidine but with 5% glucose. Thereafter, the cells were treated as described for panel A. The values shown are the average results and standard deviations from three replicate experiments. (C) ADH2 mRNA made in derepressing conditions under the control of the chimeric Adr1-EV activator is not subject to glucose-induced mRNA decay. Cultures of strain TYY204 (adr1Δ) carrying the chimeric gene ADR1-EV were grown, derepressed, and induced as described for panel A. After 60 min of induction, glucose and 1,10-o-phenanthroline were added to final concentrations of 5% and 100 μg/ml, respectively. Aliquots were removed at the times indicated for RNA isolation and analysis. The results shown are those of a representative example from three replicate experiments.