Figure 2.
Effect of thioredoxin deletion on p53 activity in thioredoxin reductase null yeast. For each transformation group, six independent transformants were assayed for β-galactosidase activity. Bars represent activity levels (mean ± S.D.), normalized to the level in wild-type yeast expressing native p53. Asterisk (*) indicates genotypes where p53 activity in wild-type and mutant yeast differed significantly (p < 0.05, by t-test). A. Effect of deleting thioredoxin on p53-dependent reporter gene expression in thioredoxin reductase null cells. Strains with the indicated genotypes were co-transformed with the pRS314PGK-p53 effector and pRS316-p53RE-LacZ reporter plasmids. B. Levels of p53-dependent reporter gene expression in yeast inheriting different combinations of the Δtrr1, Δtrx1 and Δtrx2 null alleles. A diploid that was heterozygous for null mutations in the TRR1, TRX1 and TRX2 genes was sporulated, and tetrad segregants representing the eight possible haplotypes were isolated and co-transformed with the pRS314PGK-p53 effector and pRS316-p53RE-LacZ reporter plasmids.