title: Functional characterization of the antagonistic flagellar late regulators FliA and FlgM of Helicobacter pylori and their effects on the H. pylori transcriptome.
abstract: Helicobacter pylori is thought to regulate gene expression with a very small set of regulatory genes. We identified a previously unannotated open reading frame (ORF) in the H. pylori 26695 genome (HP1122) as a putative H. pylori flgM gene (sigma28 factor antagonist) by a motif-based bioinformatic approach. Deletion of HP1122 resulted in a fourfold increase in transcription of the sigma28-dependent major flagellin gene flaA, supporting the function of HP1122 as H. pylori FlgM. Helicobacter pylori FlgM lacks a conserved 20-amino-acid N-terminal domain of enterobacterial FlgM proteins, but was able to interact with the Salmonella typhimurium sigma28 (FliA) and inhibit the expression of FliA-dependent genes in Salmonella. Helicobacter pylori FlgM inhibited FliA to the same extent in a Salmonella strain with an intact flagellar export system and in an export-deficient strain. Helicobacter pylori FliA was able to drive transcription of FliA-dependent genes in Salmonella. The effects of mutations in the H. pylori flgM and fliA genes on the H. pylori transcriptome were analysed using whole genome DNA microarrays. The antagonistic roles of FlgM and FliA in controlling the transcription of the major flagellin gene flaA were confirmed, and two additional FliA/FlgM dependent operons (HP472 and HP1051/HP1052) were identified. None of the three genes contained in these operons has a known function in flagellar biogenesis in other bacteria. Like other motile bacteria, H. pylori has a FliA/FlgM pair of sigma and anti-sigma factors, but the genes controlled by these differ markedly from the Salmonella/Escherichia coli paradigm.
authors: Institute for Hygiene and Microbiology, University of Wuerzburg, Germany. cjosenhans@hygiene.uni-wuerzburg.de
authors: Christine
authors: C
authors: Josenhans
authors: Eike
authors: E
authors: Niehus
authors: Stefanie
authors: S
authors: Amersbach
authors: Andrea
authors: A
authors: Hörster
authors: Christian
authors: C
authors: Betz
authors: Bernd
authors: B
authors: Drescher
authors: Kelly T
authors: KT
authors: Hughes
authors: Sebastian
authors: S
authors: Suerbaum
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D005407:Flagella; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D016480:Helicobacter pylori / Q000235:genetics*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D020411:Oligonucleotide Array Sequence Analysis; D009876:Operon; D012486:Salmonella typhimurium / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012808:Sigma Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C064971:FliA protein, Bacteria; D012808:Sigma Factor; C071266:FlgM protein, Bacteria