FIG. 3.
Electrophoretic mobility shift assays. The DNA probe (the putative crp-like cis-acting element 110 nucleotides upstream of the GTG start codon) together with an excess (1,500-fold) of nonspecific salmon sperm DNA (Sigma) was diluted in DNA-binding buffer (10 mM Tris-HCl [pH 7.5], 50 mM KCl, 1 mM Na2EDTA, 5% glycerol) and added to 55 μg of total cytoplasmic extracts. Lane 1, DNA probe alone; lane 2, DNA probe plus cell extract from SAF1 mutant; lane 3, DNA probe plus cell extract from S. coelicolor wild type. Percentages indicate the proportions of the various shifts. Each experiment was repeated at least three times.