This Article Full Text Full Text (PDF) Other Versions of this Article: IAI.00993-07v1 76/2/497    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bury-Moné, S. Articles by De Reuse, H. Search for Related Content PubMed PubMed Citation Articles by Bury-Moné, S. Articles by De Reuse, H.

 Previous Article  |  Next Article 

Infection and Immunity, February 2008, p. 497-509, Vol. 76, No. 2
0019-9567/08/$08.00+0     doi:10.1128/IAI.00993-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Roles of and β Carbonic Anhydrases of Helicobacter pylori in the Urease-Dependent Response to Acidity and in Colonization of the Murine Gastric Mucosa

Stéphanie Bury-Moné,^1, George L. Mendz,² Graham E. Ball,² Marie Thibonnier,¹ Kerstin Stingl,^1, Chantal Ecobichon,¹ Patrick Avé,³ Michel Huerre,³ Agnès Labigne,¹ Jean-Michel Thiberge,¹ and Hilde De Reuse^1*

Unité de Pathogénie Bactérienne des Muqueuses, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France,¹ School of Medical Sciences, The University of New South Wales, Sydney NSW, Australia,² Unité d'Histopathologie, Institut Pasteur, 75724 Paris Cedex 15, France³

Received 20 July 2007/ Returned for modification 6 September 2007/ Accepted 5 November 2007

Carbon dioxide occupies a central position in the physiology of Helicobacter pylori owing to its capnophilic nature, the large amounts of carbon dioxide produced by urease-mediated urea hydrolysis, and the constant bicarbonate supply in the stomach. Carbonic anhydrases (CA) catalyze the interconversion of carbon dioxide and bicarbonate and are involved in functions such as CO₂ transport or trapping and pH homeostasis. H. pylori encodes a periplasmic -CA (-CA-HP) and a cytoplasmic β-CA (β-CA-HP). Single CA inactivation and double CA inactivation were obtained for five genetic backgrounds, indicating that H. pylori CA are not essential for growth in vitro. Bicarbonate-carbon dioxide exchange rates were measured by nuclear magnetic resonance spectroscopy using lysates of parental strains and CA mutants. Only the mutants defective in the -CA-HP enzyme showed strongly reduced exchange rates. In H. pylori, urease activity is essential for acid resistance in the gastric environment. Urease activity measured using crude cell extracts was not modified by the absence of CA. With intact CA mutant cells incubated in acidic conditions (pH 2.2) in the presence of urea there was a delay in the increase in the pH of the incubation medium, a phenotype most pronounced in the absence of H. pylori -CA. This correlated with a delay in acid activation of the urease as measured by slower ammonia production in whole cells. The role of CA in vivo was examined using the mouse model of infection with two mouse-adapted H. pylori strains, SS1 and X47-2AL. Compared to colonization by the wild-type strain, colonization by X47-2AL single and double CA mutants was strongly reduced. Colonization by SS1 CA mutants was not significantly different from colonization by wild-type strain SS1. However, when mice were infected by SS1 (β-CA-HP) or by a SS1 double CA mutant, the inflammation scores of the mouse gastric mucosa were strongly reduced. In conclusion, CA contribute to the urease-dependent response to acidity of H. pylori and are required for high-grade inflammation and efficient colonization by some strains.

Published ahead of print on 19 November 2007.

Editor: V. J. DiRita

Present address: Laboratoire de Biotechnologies et Pharmacologie génétique Appliquée (LBPA), UMR CNRS 8113, ENS-Cachan, Cachan Cedex 94235, France.

Present address: Institut für Allgemeine Zoologie und Genetik, Westfälische Wilhelms-Universität, 48149 Münster, Germany.