FIG 3.

DNA-binding activities of EspR mutants. Electrophoretic mobility shift assay (EMSA) using a 1 nM concentration of a specific 63-bp dsDNA fragment of the espA promoter (5) and indicated amounts of purified wt or mutated His₉-tagged EspR (A) or untagged versions of the EspR wt or variants (B) displaying no shift in panel A. “B” means bound protein (protein-DNA complex). The EspRΔ10, R70A, R101A, and K72A mutants are characterized by a smaller-mobility shift and a lower affinity for DNA than the wt protein.