Staying alive overdosed: How does control urease activity?

Stingl, Kerstin

doi:10.1016/j.ijmm.2005.06.006

Cited by 92 publications

(83 citation statements)

References 61 publications

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“…3a). To eliminate the effect of low-level urea production from bacterial nitrogen metabolism (Stingl & De Reuse, 2005), which may affect acid survival, we compared the survival of YpIII in defined M9 medium (without tryptone, yeast extract or other potential urea-containing materials) at pH 4.5; we found no obvious difference in cell survival rates between YpIII and DureC (data not shown). This strongly suggests that the role of urease in acid survival is also ureadependent.…”

Section: Discussionmentioning

confidence: 99%

“…Urease, a nickel metalloenzyme catalysing the hydrolysis of urea to form carbon dioxide and ammonia, was shown to enhance acid tolerance in Yersinia enterocolitica (De Koning-Ward & Robins-Browne, 1995;Young et al, 1996) and the AR in H. pylori (Marshall et al, 1990). It has been proposed that urease hydrolyses urea in animal organs and produces sufficient ammonia to raise the pH to levels at which the bacteria remain viable (Stingl & De Reuse, 2005).…”

Section: Introductionmentioning

confidence: 99%

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OmpR positively regulates urease expression to enhance acid survival of Yersinia pseudotuberculosis

Wang

et al. 2009

Microbiology

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Yersinia pseudotuberculosis is an enteric bacterium which must overcome the acidic stress in host organs for successful colonization, but how this bacterium survives in acidic conditions remains largely unknown. In the present study, the importance of OmpR in acid survival of Y. pseudotuberculosis YpIII was confirmed by the fact that mutation of ompR (strain ΔompR) greatly reduced cell survival at pH 4.5 or lower. To characterize the regulatory role of OmpR in this acid survival process, proteomic analysis was carried out to compare YpIII at pH 7.0 and pH 4.5 with ΔompR at pH 7.0, and urease components were revealed to be the main targets for OmpR regulation. Addition of urea to the culture medium also enhanced acid survival of YpIII but not ΔompR and urease activity was significantly induced by acid in YpIII but not in ΔompR. Each of the seven components of the YpIII urease gene cluster was fused to a lacZ reporter and their expression was dramatically decreased in a ΔompR background; this supports the notion that OmpR positively regulates urease expression. Furthermore, gel shift analysis revealed that OmpR binds to the deduced promoter regions of three polycistronic transcriptional units (ureABC, ureEF and ureGD) in the urease cluster, suggesting that the regulation of OmpR to urease components is direct. Taken together, these data strongly suggest that OmpR activates urease expression to enhance acid survival in Y. pseudotuberculosis.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

OmpR positively regulates urease expression to enhance acid survival of Yersinia pseudotuberculosis

Wang

et al. 2009

Microbiology

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“…It is proposed that urease activity is modulated by nickel efflux via CznABC to reduce Ni-activated urease levels, and that efflux of other metals such as cadmium and zinc prevents urease inhibition. The model is strengthened by the observations that considerable apourease (devoid of nickel) is oftentimes observed in H. pylori, so that intracellular nickel levels would be expected to rapidly affect urease activity via enzyme activation/inactivation (Stingl and De Reuse 2005). An example of the importance of metal cation discrimination to H. pylori physiology is highlighted by the unique properties described for this Czn pump complex.…”

Section: The Czna Bc Metal Efflux Pumpmentioning

confidence: 99%

“…While Hpn is a predominant protein in H. pylori, we have no information on the relative amount of Hpn-like that is synthesized. Only a minor percentage of H. pylori urease is Ni-activated (Stingl and De Reuse, 2005) and that nickel can be a factor sometimes limiting urease activity rather than activity being limited by the amount of urease protein (van Vliet et al 2001). It was observed that addition of just 1 µM nickel to the growth medium increased the urease activities but did not cause an increase in urease expression levels (van Vliet et al 2002) and disrupting H. pylori genes encoding a metal efflux pump (cznABC) led to an increase in urease activity (Stahler et al 2006), presumably by making cytosolic nickel available.…”

Section: Hpn and Hpn-like Proteinsmentioning

confidence: 99%

Nickel-binding and accessory proteins facilitating Ni-enzyme maturation in Helicobacter pylori

2007

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Helicobacter pylori colonizes the human gastric mucosa and this can lead to chronic gastritis, peptic and duodenal ulcers, and even gastric cancers. The bacterium colonizes over one-half of the worlds population. Nickel plays a major role in the bacteriums colonization and persistence attributes as two nickel enzyme sinks obligately contain the metal. Urease accounts for up to 10% of the total cellular protein made and is required for initial colonization processes, and the hydrogen oxidizing hydrogenase provides the bacterium a high-energy substrate yielding low potential electrons for energy generation. A battery of accessory proteins are needed for maturation or activation of each of the apoen-zymes. These include Ni-chaperones and GTPas-es, some of which are unique to each Ni-enzyme and others that are individually required for maturation of both the Ni-enzymes. H. pylori's need for some conventional hydrogenase maturation proteins playing roles in urease maturation may have to do with the poor nickel-sequestering ability of the UreE urease maturation protein compared to other systems. H. pylori also possesses a NixA nickel specific permease, a nickel dependent regulator (NikR), a recently identified nickel efflux system (CznABC), and a histidinerich heat shock protein, HspA. Based on mutant analysis approaches all these proteins have roles in nickel homeostasis, in urease expression, and in host colonization. The His-rich putative nickel storage proteins Hpn and Hpn-like play roles in nickel detoxification and may influence the levels of Ni-activated urease that can be achieved.

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“…Its urease enzyme, a Ni 2+ -containing dodecameric protein of approximately 1100 kDa, composed of 12 small subunits, UreA (27 kDa), and 12 large subunits, UreB (62 kDa), catalyzes the hydrolysis of urea into ammonia and carbon dioxide, buffering both the bacteria cytoplasm and periplasm [39]. Accounting for 5-10% of the total protein content, urease is one of the most abundant proteins in the H. pylori proteome [16,30].…”

Section: Acid Resistance and Motilitymentioning

confidence: 99%