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Journal of Bacteriology, August 2009, p. 4824-4834, Vol. 191, No. 15
0021-9193/09/$08.00+0 doi:10.1128/JB.00018-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
The Helicobacter pylori Anti-Sigma Factor FlgM Is Predominantly Cytoplasmic and Cooperates with the Flagellar Basal Body Protein FlhA 
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Melanie Rust,1
Sophie Borchert,1
Eike Niehus,1,
Sarah A. Kuehne,1,
Eugenia Gripp,1
Afrodita Bajceta,1
Jonathan L. McMurry,3
Sebastian Suerbaum,1
Kelly T. Hughes,2 and
Christine Josenhans1*
Department for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany,1 Department of Biology, University of Utah, Salt Lake City, Utah,2 Department of Chemistry and Biochemistry, Kennesaw State University, Kennesaw, Georgia3
Received 7 January 2009/ Accepted 5 May 2009
Helicobacter pylori requires flagellar motility and orientation to persist actively in its habitat. A particular feature of flagella in most Helicobacter species including H. pylori is a membraneous flagellar sheath. The anti-sigma factor FlgM of H. pylori is unusual, since it lacks an N-terminal domain present in other FlgM homologs, e.g., FlgM of Salmonella spp., whose regulatory function is intimately coupled to its secretion through the flagellar type III secretion system. The aim of the present study was to characterize the localization and secretion of the short H. pylori FlgM in the presence of a flagellar sheath and to elucidate its interaction with other flagellar proteins, such as the basal body protein FlhA, which was previously shown to cooperate with FlgM for regulation. H. pylori FlgM was only released into the medium in minor amounts in wild-type bacteria, where the bulk amount of the protein was retained in the cytoplasm. Some FlgM was detected in the flagellar fraction. FlgM was expressed in flhA mutants and was less soluble and differentially localized in bacterial fractions of the flhA mutant in comparison to wild-type bacteria. FlgM-green fluorescent protein and FlgM-V5 translational fusions were generated and expressed in H. pylori. FlgM displayed a predominantly polar distribution and interacted with the C-terminal domain of FlhA (FlhAC). We suggest that, in H. pylori, FlgM secretion may not be paramount for its regulatory function and that protein interactions at the flagellar basal body may determine the turnover and localization of functional FlgM.
* Corresponding author. Mailing address: Hannover Medical School, Institute for Medical Microbiology, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany. Phone: 49 511 532 4348. Fax: 49 511 532 4355. E-mail: josenhans.Christine{at}mh-hannover.de
Published ahead of print on 22 May 2009.
Supplemental material for this article may be found at http://jb.asm.org/.
Present address: RMC Consulting, Rheinfelden, Germany.
Present address: Institute for Infection, Immunity and Inflammation, University of Nottingham, Nottingham, United Kingdom.
Journal of Bacteriology, August 2009, p. 4824-4834, Vol. 191, No. 15
0021-9193/09/$08.00+0 doi:10.1128/JB.00018-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»