This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Roncarati, D.
Right arrow Articles by Scarlato, V.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Roncarati, D.
Right arrow Articles by Scarlato, V.

 Previous Article  |  Next Article 

Journal of Bacteriology, October 2007, p. 7234-7243, Vol. 189, No. 20
0021-9193/07/$08.00+0     doi:10.1128/JB.00626-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Transcriptional Regulation of Stress Response and Motility Functions in Helicobacter pylori Is Mediated by HspR and HrcA{triangledown}

Davide Roncarati,1 Alberto Danielli,1 Gunther Spohn,2,{dagger} Isabel Delany,2 and Vincenzo Scarlato1,2*

Department of Biology, University of Bologna, Bologna, Italy,1 Molecular Immunology Unit, Novartis Vaccines, Siena, Italy2

Received 23 April 2007/ Accepted 30 July 2007

The hrcA and hspR genes of Helicobacter pylori encode two transcriptional repressor proteins that negatively regulate expression of the groES-groEL and hrcA-grpE-dnaK operons. While HspR was previously shown to bind far upstream of the promoters transcribing these operons, the binding sites of HrcA were not identified. Here, we demonstrate by footprinting analysis that HrcA binds to operator elements similar to the so-called CIRCE sequences overlapping both promoters. Binding of HspR and HrcA to their respective operators occurs in an independent manner, but the DNA binding activity of HrcA is increased in the presence of GroESL, suggesting that the GroE chaperonin system corepresses transcription together with HrcA. Comparative transcriptome analysis of the wild-type strain and hspR and hrcA singly and doubly deficient strains revealed that a set of 14 genes is negatively regulated by the action of one or both regulators, while a set of 29 genes is positively regulated. While both positive and negative regulation of transcription by HspR and/or HrcA could be confirmed by RNA primer extension analyses for two representative genes, binding of either regulator to the promoters could not be detected, indicating that transcriptional regulation at these promoters involves indirect mechanisms. Strikingly, 14 of the 29 genes which were found to be positively regulated by HspR or HrcA code for proteins involved in flagellar biosynthesis. Accordingly, loss of motility functions was observed for HspR and HrcA single or double mutants. The possible regulatory intersections of the heat shock response and flagellar assembly are discussed.

* Corresponding author. Mailing address: Department of Biology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy. Phone: 39 051 209 4204. Fax: 39 051 209 4286. E-mail: vincenzo.scarlato{at}unibo.it

{triangledown} Published ahead of print on 10 August 2007.

{dagger} Present address: Cytos Biotechnology, Wagistrasse 25, 8952 Zürich-Schlieren, Switzerland.

Journal of Bacteriology, October 2007, p. 7234-7243, Vol. 189, No. 20
0021-9193/07/$08.00+0     doi:10.1128/JB.00626-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Smith, T. G., Pereira, L., Hoover, T. R. (2009). Helicobacter pylori FlhB processing-deficient variants affect flagellar assembly but not flagellar gene expression. Microbiology 155: 1170-1180 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»