title: The NudA protein in the gastric pathogen Helicobacter pylori is an ubiquitous and constitutively expressed dinucleoside polyphosphate hydrolase.
abstract: 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, Ap(4)A at a k(cat) of 0.15 s(-1) and a K(m) of 80 microm, 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.
authors.affiliation: Department of Bacteriology, Swedish Institute for Infectious Disease Control, 171 82 Solna, Sweden.
authors.forename: Annelie
authors.initials: A
authors.lastname: Lundin
authors.forename: Christina
authors.initials: C
authors.lastname: Nilsson
authors.forename: Markus
authors.initials: M
authors.lastname: Gerhard
authors.forename: Dan I
authors.initials: DI
authors.lastname: Andersson
authors.forename: Margareta
authors.initials: M
authors.lastname: Krabbe
authors.forename: Lars
authors.initials: L
authors.lastname: Engstrand
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D015226:Dinucleoside Phosphates / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D016254:Mutagenesis, Insertional; D018384:Oxidative Stress / Q000502:physiology; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D015226:Dinucleoside Phosphates; D006867:Hydrolases