, Volume 43, Issue 11, pp 849-857
Date: 18 Nov 2008

Cloning, polymorphism, and inhibition of β-carbonic anhydrase of Helicobacter pylori

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Abstract

Background

Carbonic anhydrase (CA) catalyzes the reversible hydration of CO2 to bicarbonate and a proton, and α-class CA has been reported to facilitate the acid acclimation of Helicobacter pylori (hpαCA). The purpose of this study was to characterize the β-class CA of H. pylori (hpβCA) and elucidate the role of this enzyme as a possible drug target for eradication therapy.

Methods

We isolated DNA clones of independent H. pylori strains obtained from patients with gastritis (n = 15), gastric ulcer (n = 6), or gastric cancer (n = 16), and then studied genetic polymorphisms. In addition, the susceptibility of H. pylori to sulpiride, an antiulcer drug and efficient inhibitor of both hpαCA and hpβCA, was studied with an in vitro killing assay.

Results

DNA sequences of all 37 hpβCA clones encoded a 221 amino acid polypeptide with a variety of polymorphisms (57 types of amino acid substitution at 48 residue positions). There was no polymorphism functionally relevant to the gastric lesion type. One strain included unique residues that were not seen in the other 36 clones from Japanese patients but which were found in a strain obtained from the United Kingdom. Sulpiride had killing effects at concentrations greater than 200 μg/ml for H. pylori, including strains resistant to clarithromycin, metronidazole, or ampicillin.

Conclusions

Helicobacter pylori might have evolved independently in the Caucasian and Japanese populations. Dual inhibition of α-and β-class CAs could be applied as alternative therapy for eradication of H. pylori.