Figure 2.

The TFIIB mutant YR1m4 is defective in supporting activated gene expression in vivo. (A) A CYC1_TATA-lacZ reporter plasmid with (pM1820) (31) or without (pLG670Z) (31) CTS1_UAS element was introduced into yeast strain 604 containing a plasmid expressing either wild-type TFIIB or YR1m4. The absolute activities are 1.58, 101.54, 1.0 and 2.68 U β-galactosidase in columns 1–4, respectively. (B) A LexA_OP-CYC1_TATA-lacZ reporter plasmid was introduced into the same strain as in (A). Plasmids that express either LexA-VP16 or LexA were transformed into the cells and assayed for β-galactosidase activity. The absolute β-galactosidase units are 4.6, 100.5, 2.8 and 6.4 in columns 1–4, respectively. All assays were done using three independent transformants in duplicate. The SDs are <20% in all cases.