Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:6.3.4.6 (
urease
)
7,490
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
ureI encodes an inner membrane protein of Helicobacter pylori. The role of the bacterial inner membrane and UreI in acid protection and regulation of cytoplasmic
urease
activity in the gastric microorganism was studied. The irreversible inhibition of
urease
when the organism was exposed to a protonophore (3,3',4', 5-tetrachlorsalicylanide;
TCS
) at acidic pH showed that the inner membrane protected
urease
from acid. Isogenic ureI knockout mutants of several H. pylori strains were constructed by replacing the ureI gene of the
urease
gene cluster with a promoterless kanamycin resistance marker gene (kanR). Mutants carrying the modified ureAB-kanR-EFGH operon all showed wild-type levels of
urease
activity at neutral pH in vitro. The mutants resisted media of pH > 4.0 but not of pH < 4.0. Whereas wild-type bacteria showed high levels of
urease
activity below pH 4.0, this ability was not retained in the ureI mutants, resulting in inhibition of metabolism and cell death. Gene complementation experiments with plasmid-derived H. pylori ureI restored wild-type properties. The activation of
urease
activity found in structurally intact but permeabilized bacteria treated with 0.01% detergent (polyoxy-ethylene-8-laurylether; C12E8), suggested a membrane-limited access of urea to internal
urease
at neutral pH. Measurement of 14C-urea uptake into Xenopus oocytes injected with ureI cRNA showed acid activation of uptake only in injected oocytes. Acceleration of urea uptake by UreI therefore mediates the increase of intracellular
urease
activity seen under acidic conditions. This increase of urea permeability is essential for H. pylori survival in environments below pH 4.0. ureI-independent
urease
activity may be sufficient for maintenance of bacterial viability above pH 4.0.
...
PMID:Acid resistance of Helicobacter pylori depends on the UreI membrane protein and an inner membrane proton barrier. 1076 Jan 71
