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Infection and Immunity, May 1999, p. 2060-2070, Vol. 67, No. 5
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.

Molecular Characterization of a Flagellar Export Locus of Helicobacter pylori

Steffen Porwollik,1 Brian Noonan,2 and Paul W. O'Toole1,*

Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand,1 and Astra Research Center Boston, Inc., Cambridge, Massachusetts 021392

Received 31 August 1998/Returned for modification 3 November 1998/Accepted 8 February 1999

Motility of Helicobacter species has been shown to be essential for successful colonization of the host. We have investigated the organization of a flagellar export locus in Helicobacter pylori. A 7-kb fragment of the H. pylori CCUG 17874 genome was cloned and sequenced, revealing an operon comprising an open reading frame of unknown function (ORF03), essential housekeeping genes (ileS and murB), flagellar export genes (fliI and fliQ), and a homolog to a gene implicated in virulence factor transport in other pathogens (virB11). A promoter for this operon, showing similarity to the Escherichia coli sigma 70 consensus, was identified by primer extension. Cotranscription of the genes in the operon was demonstrated by reverse transcription-PCR, and transcription of virB11, fliI, fliQ, and murB was detected in human or mouse biopsies obtained from infected hosts. The genetic organization of this locus was conserved in a panel of H. pylori clinical isolates. Engineered fliI and fliQ mutant strains were completely aflagellate and nonmotile, whereas a virB11 mutant still produced flagella. The fliI and fliQ mutant strains produced reduced levels of flagellin and the hook protein FlgE. Production of OMP4, a member of the outer membrane protein family identified in H. pylori 26695, was reduced in both the virB11 mutant and the fliI mutant, suggesting related functions of the virulence factor export protein (VirB11) and the flagellar export component (FliI).

* Corresponding author. Mailing address: Institute of Molecular BioSciences, Massey University, Private Bag 11222, Palmerston North, New Zealand. Phone: 64 6 350 4998. Fax: 64 6 350 5688. E-mail: P.W.O'Toole{at}Massey.ac.nz.

Infection and Immunity, May 1999, p. 2060-2070, Vol. 67, No. 5
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.


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