Figure 4

Gel mobility-shift analysis of CYS3 binding sites within the met-2⁺promoter. Lanes: 1, CYS3-binding site 1 (nt −1017 to −1026); 1 M, mutated CYS3-binding site 1; 2, CYS3-binding site 2 (nt −916 to −925); 2 M, mutated CYS3-binding site 2; 3, CYS3-binding site 3 (nt −413 to −422); 3 M, mutated CYS3-binding site 3; 4, CYS3-binding site 4 (nt −138 to −147); 4 M, mutated CYS3-binding site 4. Each CYS3 binding site was mutated with a single point mutation to determine the specificity of CYS binding.. The arrow indicates DNA fragments exhibiting reduced electrophoretic mobility due to protein-DNA interactions. The schematic of the met-2⁺ promoter (top) depicts the affinity of CYS3 for each binding site (+, weakest affinity; +++ strongest affinity) and includes the corresponding binding site nucleotide sequences for both wild type (WT) and mutated (MUT).