title: Interactions among the seven Helicobacter pylori proteins encoded by the urease gene cluster.
abstract: Survival of Helicobacter pylori in acid depends on intrabacterial urease. This urease is a Ni(2+)-containing oligomeric heterodimer. Regulation of its activity and assembly is important for gastric habitation by this neutralophile. The gene complex encodes catalytic subunits (ureA/B), an acid-gated urea channel (ureI), and accessory assembly proteins (ureE-H). With the use of yeast two-hybrid analysis for determining protein-protein interactions, UreF as bait identified four interacting sequences encoding UreH, whereas UreG as bait detected five UreE sequences. These results were confirmed by coimmunoprecipitation and beta-galactosidase assays. Native PAGE immunoblotting of H. pylori inner membranes showed interaction of UreA/B with UreI, whereas UreI deletion mutants lacked this protein interaction. Deletion of ureE-H did not affect this interaction with UreI. Hence, the accessory proteins UreE/G and UreF/H form dimeric complexes and UreA/B form a membrane complex with UreI, perhaps enabling assembly of the urease apoenzyme at the membrane surface and immediate urea access to intrabacterial urease to allow rapid periplasmic neutralization.
authors.affiliation: Department of Medicine II, Technical University, 81675 Munich, Germany. petra.voland@lrz.tum.de
authors.forename: Petra
authors.initials: P
authors.lastname: Voland
authors.forename: David L
authors.initials: DL
authors.lastname: Weeks
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Marcus
authors.forename: Christian
authors.initials: C
authors.lastname: Prinz
authors.forename: George
authors.initials: G
authors.lastname: Sachs
authors.forename: David
authors.initials: D
authors.lastname: Scott
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D004586:Electrophoresis; D005744:Gastric Acid; D016480:Helicobacter pylori / Q000201:enzymology*; D066298:In Vitro Techniques; D026901:Membrane Transport Proteins; D016296:Mutagenesis / Q000502:physiology; D028044:Phosphate-Binding Proteins; D011233:Precipitin Tests; D020798:Two-Hybrid System Techniques; D014510:Urease / Q000235:genetics* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D028044:Phosphate-Binding Proteins; C090404:UreE protein, Bacteria; C101639:UreF protein, bacteria; C114527:UreI protein, Helicobacter pylori; C082270:ureG protein, Bacteria; D014510:Urease