Linked Life Data

10760171

Source:http://linkedlifedata.com/resource/pubmed/id/10760171

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2000-5-23
pubmed:abstractText
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.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0950-382X
pubmed:author
pubmed:issnType
Print
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
141-52
pubmed:dateRevised
2003-11-14
pubmed:meshHeading
pubmed-meshheading:10760171-Acids, pubmed-meshheading:10760171-Animals, pubmed-meshheading:10760171-Bacterial Proteins, pubmed-meshheading:10760171-Biological Transport, pubmed-meshheading:10760171-Culture Media, pubmed-meshheading:10760171-Drug Resistance, Microbial, pubmed-meshheading:10760171-Helicobacter pylori, pubmed-meshheading:10760171-Hydrogen-Ion Concentration, pubmed-meshheading:10760171-Ionophores, pubmed-meshheading:10760171-Membrane Transport Proteins, pubmed-meshheading:10760171-Multigene Family, pubmed-meshheading:10760171-Proton-Motive Force, pubmed-meshheading:10760171-Protons, pubmed-meshheading:10760171-Recombinant Proteins, pubmed-meshheading:10760171-Salicylanilides, pubmed-meshheading:10760171-Urea, pubmed-meshheading:10760171-Urease, pubmed-meshheading:10760171-Xenopus
pubmed:year
2000
pubmed:articleTitle
Acid resistance of Helicobacter pylori depends on the UreI membrane protein and an inner membrane proton barrier.
pubmed:affiliation
Department of Molecular Biology, Byk Gulden Pharmaceuticals Konstanz, Germany.
pubmed:publicationType
Journal Article