Figure 3

Gel mobility-shift analysis of CYS3 binding. Lanes: 1, CYS3-binding site 1 (nt −829 to −838); 1 M, mutated CYS3-binding site 1; 2, CYS3-binding site 2 (nt −531 to −540); 2 M, mutated CYS3-binding site 2; 3, CYS3-binding site 3 (nt −271 to −280); 3 M, mutated CYS3-binding site 3; 4, CYS3-binding site 4 (nt −128 to −137); 4 M, mutated CYS3-binding site 4. A single nucleotide within each CYS3 binding site was mutated to determine the specificity of CYS3 binding. The arrow indicates DNA fragments exhibiting reduced electrophoretic mobility due to protein-DNA interactions. The affinity of CYS3 for each binding site is depicted in the schematic of the cys-16⁺ promoter (top) (+, weakest affinity; +++ strongest affinity).