Figure 1.

Transcriptional activation by CBF1 in yeast requires the yeast ADA2, ADA3 and GCN5 genes. A reporter gene consisting of two CRT/DRE cis-acting sequences inserted 5′ to a GAL1 minimal promoter–lacZ gene fusion was integrated into the URA3 locus of the wild-type parental yeast strain PSY316 and the respective isogenic ada2, ada3 and gcn5 deletion mutant strains. These strains were transformed with a 2µ plasmid carrying the CBF1 coding sequence under control of the constitutive promoter ADC1 and were grown to mid-log phase (OD₅₉₀ = 0.6 to 0.8) before cell extracts were assayed for β-galactosidase activity (31). Values for β-galactosidase activity were normalized to total yeast cellular protein. Error bars represent the standard deviation about the mean for three independent yeast cultures.