FIG. 6.

Gel mobility shift assays of the txeR promoter. A DNA fragment containing the txeR promoter region (P1+P2) was incubated with C. difficile RNA polymerase (A) or E. coli RNA polymerase (B) core enzyme alone or core enzyme that had been preincubated with TxeR (see Materials and Methods). The triangle in panel B indicates the use of increasing amounts of TxeR-containing holoenzyme (100 and 200 nM). (C) A DNA fragment containing the E. coli lacUV5 promoter was incubated with E. coli core enzyme alone or core enzyme that had been preincubated with TxeR or E. coli σ⁷⁰.