Figure 4.

In vitro transcription activation from tox promoters by RNA polymerase and TxeR. In vitro run-off transcription reactions were performed by using RNA polymerases from E. coli (Ec), B. subtilis (Bs), or C. difficile (Cd) and DNA fragments containing either the toxA promoter (PtoxA) or the toxB promoter (PtoxB) incubated in the absence or presence of partially purified TxeR. A control transcription reaction performed on the gdh promoter DNA with C. difficile RNA polymerase is shown in the leftmost lane. The expected sizes of run-off transcripts (indicated by arrows) are: Pgdh, 162 nt; PtoxA, 255 nt; PtoxB, 175 nt. An additional read-through transcript of 291 nt is made from the gdh promoter.