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Articles in PresS, published online ahead of print September 4, 2002
Am J Physiol Gastrointest Liver Physiol, 10.1152/ajpgi.00160.2002
Submitted on May 1, 2002
Accepted on August 21, 2002
1 Department of Medicine II, Technical University, Munich, Germany
2 VAGLAHS, UCLA, Los Angeles, CA, USA
* To whom correspondence should be addressed. E-mail: petra.voland{at}lrz.tum.de.
Survival of Helicobacter pylori in acid depends on intrabacterial urease. This urease is a Ni2+-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 (ureEFGH). Using yeast-two hybrid analysis (Y2H) for determining protein-protein interactions, UreF as bait identified 4 interacting sequences encoding UreH while, UreG as bait detected, 5 UreE sequences. These results were confirmed by co-immunoprecipitation and ß-galactosidase assays. Native PAGE immunoblotting of H. pylori inner membranes showed interaction of UreA/B with UreI, while UreI deletion mutants lacked this protein interaction. Deletion of ureE, F, G and H did not affect this interaction with UreI. Hence, the accessory proteins UreE/G and UreF/H form dimeric complexes and UreA/B forms a membrane complex with UreI, perhaps enabling assembly of the urease apo-enzyme at the membrane surface and immediate urea access to intra-bacterial urease to allow rapid periplasmic neutralization.
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