Acidic media trigger cytoplasmic urease activity of the unique human gastric pathogen Helicobacter pylori. Deletion of ureI prevents this activation of cytoplasmic urease that is essential for bacterial acid resistance. UreI is an inner membrane protein with six transmembrane segments as shown by in vitro transcription/translation and membrane separation. Expression of UreI in Xenopus oocytes r...

Cryptococcus neoformans is a pathogenic basidiomycete with a defined sexual cycle involving mating between haploid yeast cells with a transient diploid state. We examined F1 progeny from a crossing between the urease-negative strain (environmental isolate, serotype A, mating type alfa, haploid) and a tester strain (B 3502 from NIH of USA; urease-positive, serotype D, mating type a, haploid) for...

Helicobacter pylori mutants devoid of urease activity fail to colonize the gastric mucosa of mice; however, the effect of decreased levels of urease on colonization has not been examined. The nixA gene, required for full urease activity, encodes a cytoplasmic membrane nickel transporter that imports nickel ions and leads to incorporation of nickel ions into apourease. A nixA mutant of the Sydne...

color from ammonia was produced by an additional 5 min of incubation at 37 C. All strains of Proteus, except those of P. inconstans, generated detectable amounts of ammonia (Table 1). None of the Escherichia organisms was urease-positive. These findings were identical with those yielded by the urease technique of Stuart et al. The sensitivity of the Berthelot color reaction permits detection of...

The identity of the enzyme urease with the octahedral globulin crystals isolated by the senior author from the jack bean in 1926 (1) has been challenged by Waldschmidt-Leitz and Steigerwaldt (2). These investigators published a paper in which they claimed that crystalline urease is not inactivated at pH 7.0 by incubation with trypsin or papain, while the protein component of the urease undergoe...

Foliar urea application on barley plants increased leaf urease activity for 5 hours with a peak of 20-fold at 2 hours. To discern the mode of urease induction, urea with or without inhibitors and [35S]methionine were incubated with leaf sections for different lengths of time. Urease was extracted, partially purified, electrophoresed, and then quantified by fluorogram. Five urease (U) isozymes w...

Cryptococcus neoformans var. neoformans (74 isolates) and C. neoformans var. gattii (44 isolates) were used to test urease activity after growth on both yeast extract-glucose-peptone agar (YEPG) and on YEPG supplemented with 100 microM EDTA. Every isolate grown on YEPG agar for 48 h at 30 degrees C produced a positive reaction within 1 h in a modified rapid urease assay at 37 degrees C. However...

background helicobacter pylori multiplies and causes infection in human gastric mucosal layer. new approaches have focused on using specific treatments, such as immunotherapy, to limit this infection. urease, as one of the most important virulent and antigenic factors of the bacterium, is a suitable target for this purpose. patients and methods in order to prepare recombinant proteins, the synt...

Microbially induced calcium carbonate precipitation (MICP) is a phenomenon based on urease activity of halotolerant and alkaliphilic microorganisms that can be used for the soil bioclogging and biocementation in geotechnical engineering. However, enrichment cultures produced from indigenous soil bacteria cannot be used for large-scale MICP because their urease activity decreased with the rate a...