FIG. 7.

Transcription from the E. coli tdc operon promoter is induced anaerobically by TcbC. Primer extension reactions were carried out with total RNA isolated from anaerobically grown cells. Lane 1, FM420/pBR322 grown in TYEP; lane 2, FM420/pBR322 grown in TGYEP; lane 3, FM420/pMU10 grown in TGYEP; lane 4, RM202/pBR322 grown in TGYEP; lane 5, RM202/pMU10 grown in TGYEP. The absence and presence of the indicated components in the assay are signified by minus and plus signs, respectively. The location of the transcription initiation site of the tdc operon is shown with an arrow. The lower transcript resulted from interaction of the oligonucleotide with an unidentified RNA transcript and was used as a convenient internal control to ensure that equivalent amounts of RNA were used.