G. Spohn et V. Scarlato, Motility of Helicobacter pylori is coordinately regulated by the transcriptional activator FlgR, an NtrC homolog, J BACT, 181(2), 1999, pp. 593-599
sigma(54) is the subunit of bacterial RNA polymerase that transcribes from
promoters with enhancer elements bound by enhancer-binding proteins. By com
puter searches of Helicobacter pylori genomic sequences, chromosomal gene d
isruption, and RNA analyses, we have identified sigma(54)-recognnzed promot
ers that regulate transcription of flagellar basal body and hook genes, as
well as the enhancer-binding protein FlgR (flagellum regulator), a transact
ivating protein of the NtrC family. We demonstrate that FlgR is required fo
r bacterial motility and transcription of five promoters for seven basal bo
dy and hook genes, In addition, FlgR acts as a repressor of transcription o
f the sigma(28)-regulated flaA flagellin gene promoter, while changes in DN
A topology repress transcription of the sigma(54)-regulated flaB flagellin
gene promoter. Our data indicate that regulation of flagellar gene expressi
on in H. pylori shows similarities with that in enterobacteriaceae and Caul
obacter.