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J. Biol. Chem., Vol. 278, Issue 14, 12574-12578, April 4, 2003

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 278/14/12574    most recent M212542200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lundin, A. Articles by Engstrand, L. Search for Related Content PubMed PubMed Citation Articles by Lundin, A. Articles by Engstrand, L. Social Bookmarking                      What's this?

The NudA Protein in the Gastric Pathogen Helicobacter pylori Is an Ubiquitous and Constitutively Expressed Dinucleoside Polyphosphate Hydrolase^*,

Annelie Lundin^§, Christina Nilsson^§, Markus Gerhard^¶, Dan I. Andersson, Margareta Krabbe, and Lars Engstrand^§**

From the  Department of Bacteriology, Swedish Institute for Infectious Disease Control, 171 82 Solna, Sweden, the ^§ Microbiology and Tumor Biology Center, Karolinska Institutet, 171 77 Stockholm, Sweden, the ^¶ Department of Medicine II, Technical University of Munich, Ismanigerstr. 22, 816 75 Munich, Germany, and  Pyrosequencing AB, Vallong. 1, 752 28 Uppsala, Sweden

The gastric pathogen Helicobacter pylori harbors one Nudix hydrolase, NudA, that belongs to the nucleoside polyphosphate hydrolase subgroup. In this work, the enzymatic activity of purified recombinant NudA protein was analyzed on a number of nucleoside polyphosphates. This predicted 18.6-kDa protein preferably hydrolyzes diadenosine tetraphosphate, Ap₄A at a k_cat of 0.15 s¹ and a K_m of 80 µM, resulting in an asymmetrical cleavage of the molecule into ATP and AMP. To study the biological role of this enzyme in H. pylori, an insertion mutant was constructed. There was a 2-7-fold decrease in survival of the mutant as compared with the wild type after hydrogen peroxide exposure but no difference in survival after heat shock or in spontaneous mutation frequency. Western blot analyses revealed that NudA is constitutively expressed in H. pylori at different growth stages and during stress, which would indicate that this protein has a housekeeping function. Given that H. pylori is a diverse species and that all the H. pylori strains tested in this study harbor the nudA gene and show protein expression, we consider NudA to be an important enzyme in this bacterium.

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