FIG. 1.

Genetic selection of TBP mutants that overcome Cyc8-Tup1 repression. (A) Selection scheme. Strain JGY100, which contains the HIS3 structural gene driven by the SUC2 promoter, was transformed with TBP mutant libraries, and colonies were selected for increased HIS3 expression by growth in the absence of histidine. (B) Growth of 10⁴ cells of JGY100 harboring the indicated TBP derivatives on −Ura, −Trp, and −His plates containing either 0.05 or 2% glucose. wt, wild type. Asterisks indicate mutated TBPs in libraries.