Medium pH-dependent redistribution of the urease of Helicobacter pylori

Wu, Hong; Sano, Kohei; Morimatsu, Shinichi; Scott, David; Weeks, David L.; Sachs, George; Goto, Toshiyuki; Mohan, Sharad; Harada, Fumiue; Nakajima, Norihito; Nakano, Takashi

doi:10.1099/jmm.0.05072-0

Cited by 39 publications

(48 citation statements)

References 19 publications

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“…Immunoelectron microscopy showed an acid-and UreI-dependent reorganization of UreA and UreB from a predominately cytoplasmic location to the membrane, and native PAGE identified a UreA-UreB-UreI membrane complex (13,40). In the current study, using Western blot analysis, it was found that the transition from a neutral pH to an acidic pH for 30 min resulted in a ϳ2-fold increase in the levels of UreA and UreB at the membrane in the wild-type organism.…”

Section: Discussionmentioning

confidence: 89%

Role of the Helicobacter pylori Sensor Kinase ArsS in Protein Trafficking and Acid Acclimation

et al. 2012

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Helicobacter pylori survives and grows at low pHs via acid acclimation mechanisms that enable periplasmic pH homeostasis. Important components include a cytoplasmic urease; a pH-gated urea channel, UreI; and periplasmic ␣-carbonic anhydrase. To allow the rapid adjustment of periplasmic pH, acid acclimation components are recruited to the inner membrane in acid. The ArsRS two-component system, in an acid-responsive manner, controls the transcription of the urease gene cluster and ␣-carbonic anhydrase. The aim of this study is to determine the role of ArsS in protein trafficking as a component of acid acclimation. H. pylori wild-type and ⌬arsS bacteria were incubated at acidic and neutral pHs. Intact bacteria, purified membranes, and total protein were analyzed by Western blotting and urease activity measurements. The total urease activity level was decreased in the ⌬arsS strain, but the acid activation of UreI was unaffected. A 30-min acid exposure increased the level and activity of urease proteins at the membrane in the wild type but not in the ⌬arsS strain. The urease levels and activity of the ⌬arsS strain after a 90-min acid exposure were similar to those of the wild type. ArsS, in addition to its role in urease gene transcription, is also involved in the recruitment of urease proteins to the inner membrane to augment acid acclimation during acute acid exposure. Urease membrane recruitment following prolonged acid exposure in the absence of ArsS was similar to that of the wild type, suggesting a compensatory mechanism, possibly regulated by FlgS, underscoring the importance of urease membrane recruitment and activation in periplasmic pH homeostasis.

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Section: Discussionmentioning

confidence: 89%

Role of the Helicobacter pylori Sensor Kinase ArsS in Protein Trafficking and Acid Acclimation

et al. 2012

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“…It can be envisioned that the small proportion of activated urease is sequestered in a compartment of the cell to improve its activity in connection for instance with the ammonium-incorporating enzyme, glutamine synthetase, under conditions of normal growth or with the urea inner membrane channel, UreI, for efficient substrate delivery upon acid stress. Accordingly a UreI-dependent membrane association of urease was reported previously (47,61).…”

Section: Table I Tap-tagged Proteinsmentioning

confidence: 99%

In Vivo Interactome of Helicobacter pylori Urease Revealed by Tandem Affinity Purification

Stingl

Schauer

Ecobichon

et al. 2008

Molecular & Cellular Proteomics

102

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In the human gastric bacterium Helicobacter pylori, two metalloenzymes, hydrogenase and urease, are essential for in vivo colonization, the latter being a major virulence factor. The UreA and UreB structural subunits of urease and UreG, one of the accessory proteins for Ni 2؉ incorporation into apourease, were taken as baits for tandem affinity purification. The method allows the purification of protein complexes under native conditions and physiological expression levels of the bait protein. Protein-protein interactions are operative at the majority of cellular processes; thus, their study gives valuable insight into proteomic and functional associations. Helicobacter pylori is a Gram-negative bacterium that is infecting the stomach of about half of the human population. It is responsible for the development of gastric pathologies such as gastritis, gastroduodenal ulcer, and adenocarcinoma (1). One remarkable feature of H. pylori is its capacity to persist (often during decades) and multiply in the hostile environment of the stomach. In H. pylori, urease is a major virulence factor and is essential for the resistance to acidity because of its capacity to hydrolyze urea into bicarbonate and ammonia (2), which results in pH homeostasis of the bacterium. The protein is an extremely active and highly regulated member of the nickel metalloenzyme family. Activation of urease, i.e. incorporation of nickel into the active site, requires urease-specific accessory proteins whose homologues have been extensively studied genetically and biochemically in Klebsiella pneumoniae (3)(4)(5)(6)(7)(8). It is still enigmatic why vast amounts of urease, up to 10% of the total protein, are produced, whereas only a minor active portion is sufficient for acid resistance (9). Furthermore the observation that urease is even indispensable for the colonization under neutral conditions (10) suggested additional essential functions for this central enzyme that remained unidentified.H. pylori possesses another nickel-containing enzyme, a [NiFe] hydrogenase, allowing this organism to utilize hydrogen as an energy source. Accordingly hydrogenase has been shown to be essential for H. pylori colonization in the mouse model (11). The assembly of the [NiFe] hydrogenase metal center located in the large hydrogenase subunit is partially understood and requires several proteins involved in the sequential delivery of iron before nickel (for a review, see Ref. 12). In addition, the [NiFe] hydrogenase possesses a small subunit containing [Fe-S] clusters. For the assembly of the latter no distinct biosynthetic pathway has been attributed so far, suggesting that the housekeeping [Fe-S] cluster assembly system might be involved (12). H. pylori is unique in that the maturation events of these two nickel-containing essential proteins are interconnected as H. pylori mutants deficient in one of the accessory proteins, HypA or HypB, involved in nickel insertion into hydrogenase, lack significant activation of urease (13).

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“…The proton-gated urea channel UreI regulates the rate of the urea entry into the cytoplasm and is required for acid survival and gastric infection (151,205,237). When UreI is activated by an acidic pH of the medium, urease moves from the inner portion to the outer portion of H. pylori, closer to the source of urea, so presumably ammonia production occurs at or near the inner membrane (110). In H. felis, a second urease system, UreA2B2, has been detected (180), but its function and regulation are currently unknown.…”

Section: Virulence Factors Of Gastric Non-h Pylori Helicobacter Speciesmentioning

confidence: 99%

Gastric Helicobacters in Domestic Animals and Nonhuman Primates and Their Significance for Human Health

et al. 2009

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SUMMARY Helicobacters other than Helicobacter pylori have been associated with gastritis, gastric ulcers, and gastric mucosa-associated lymphoid tissue lymphoma in humans. These very fastidious microorganisms with a typical large spiral-shaped morphology were provisionally designated “H. heilmannii,” but in fact they comprise at least five different Helicobacter species, all of which are known to colonize the gastric mucosa of animals. H. suis, which has been isolated from the stomachs of pigs, is the most prevalent gastric non-H. pylori Helicobacter species in humans. Other gastric non-H. pylori helicobacters colonizing the human stomach are H. felis, H. salomonis, H. bizzozeronii, and the still-uncultivable “Candidatus Helicobacter heilmannii.” These microorganisms are often detected in the stomachs of dogs and cats. “Candidatus Helicobacter bovis” is highly prevalent in the abomasums of cattle but has only occasionally been detected in the stomachs of humans. There are clear indications that gastric non-H. pylori Helicobacter infections in humans originate from animals, and it is likely that transmission to humans occurs through direct contact. Little is known about the virulence factors of these microorganisms. The recent successes with in vitro isolation of non-H. pylori helicobacters from domestic animals open new perspectives for studying these microorganisms and their interactions with the host.

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Medium pH-dependent redistribution of the urease of Helicobacter pylori

Cited by 39 publications

References 19 publications

Role of the Helicobacter pylori Sensor Kinase ArsS in Protein Trafficking and Acid Acclimation

Role of the Helicobacter pylori Sensor Kinase ArsS in Protein Trafficking and Acid Acclimation

In Vivo Interactome of Helicobacter pylori Urease Revealed by Tandem Affinity Purification

Gastric Helicobacters in Domestic Animals and Nonhuman Primates and Their Significance for Human Health

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