The C-terminal region of the alpha subunit of Escherichia coli RNA polymerase is required for transcriptional activation of the flagellar level II operons by the FlhD/FlhC complex.

A number of transcription activators have been found to activate transcription via protein-protein contact between RNA polymerase alpha subunits and transcription factors; they are classified as class I factors. In this report, we demonstrate that the FlhD/FlhC complex, a transcription activator of the Escherichia coli flagellar regulon, requires the C-terminal domain of the RNA polymerase alpha subunit for transcription activation. We conclude that FlhD/FlhC is a class I transcription factor.