Infection of the gastric mucosa by Helicobacter pylori remains a worldwide problem and contributes to peptic ulcer disease and gastric cancer. Without active intervention, at least 20% of the population of developed countries will continue to be infected by this gastric pathogen. Eradication of the organism would contribute to prevention of disease. Current eradication requires triple therapy, a proton-pump inhibitor and two antibiotics given twice a day for 10 to 14 days. Resistance to either clarithromycin or metronidazole is >20% and rising. No monotherapy is effective. Gastric infection by H. pylori depends on the expression of a channel unique to this pathogen, UreI. UreI is a proton-gated urea channel necessary for rapid access of urea to intrabacterial urease, essential for maintaining the periplasm at pH 6.1 in the acidic environment of the stomach, as low as pH 2.5, thus allowing colonization of the stomach. Expression of the channel is increased in the stomach. The channel has 193 residues with six transmembrane segments and three periplasmic regions. Mutagenesis studies have shown that the proton gating of UreI is regulated by hydrogen bonding between histidines and carboxylic acid residues in these three periplasmic regions. Obtaining a high-resolution 3-dimensional structure of this channel is the major goal of this work. This will enable understanding of the unique proton-gating mechanism of this protein and will provide a structure to which inhibitors, some of which have been discovered already, can be docked and their structure-activity relationship identified. Inhibition of this channel would be expected to result in specific and effective monotherapy for eradication of the organism and usher in an era of test and treat, rather than only treating symptomatic patients. This would provide a preventive approach to serious upper gastro-intestinal diseases, particularly gastric cancer.

Public Health Relevance

Infection of the human stomach by Helicobacter pylori remains an unresolved problem in both the West and underdeveloped countries. Infection increases the risk of developing gastric cancer about 20-fold. Current eradication therapy is cumbersome, requiring twice-a-day administration of a proton-pump inhibitor and two antibiotics. A high-resolution structure of the proton-gated urea channel, UreI, will provide a template for the development of inhibitors that will allow simple targeted monotherapy, allowing a test and treat strategy worldwide to prevent peptic ulcer disease and reduce the incidence of gastric adenocarcinoma.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI078000-05
Application #
8214645
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Mills, Melody
Project Start
2008-02-01
Project End
2013-07-28
Budget Start
2012-02-01
Budget End
2013-07-28
Support Year
5
Fiscal Year
2012
Total Cost
$475,359
Indirect Cost
$157,028
Name
University of California Irvine
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
046705849
City
Irvine
State
CA
Country
United States
Zip Code
92697
Dong, Bamboo; Sánchez-Magraner, Lissete; Luecke, Hartmut (2016) Structure of an Inward Proton-Transporting Anabaena Sensory Rhodopsin Mutant: Mechanistic Insights. Biophys J 111:963-72
Kryshtafovych, Andriy; Moult, John; Bales, Patrick et al. (2014) Challenging the state of the art in protein structure prediction: Highlights of experimental target structures for the 10th Critical Assessment of Techniques for Protein Structure Prediction Experiment CASP10. Proteins 82 Suppl 2:26-42
Ozorowski, Gabriel; Milton, Saskia; Luecke, Hartmut (2013) Structure of a C-terminal AHNAK peptide in a 1:2:2 complex with S100A10 and an acetylated N-terminal peptide of annexin A2. Acta Crystallogr D Biol Crystallogr 69:92-104
McNulty, Reginald; Ulmschneider, Jakob P; Luecke, Hartmut et al. (2013) Mechanisms of molecular transport through the urea channel of Helicobacter pylori. Nat Commun 4:2900
Strugatsky, David; McNulty, Reginald; Munson, Keith et al. (2013) Structure of the proton-gated urea channel from the gastric pathogen Helicobacter pylori. Nature 493:255-8
Wassman, Christopher D; Baronio, Roberta; Demir, Özlem et al. (2013) Computational identification of a transiently open L1/S3 pocket for reactivation of mutant p53. Nat Commun 4:1407
Ozorowski, Gabriel; Ryan, Christopher M; Whitelegge, Julian P et al. (2012) Withaferin A binds covalently to the N-terminal domain of annexin A2. Biol Chem 393:1151-63
Nazmi, Ali Reza; Ozorowski, Gabriel; Pejic, Milena et al. (2012) N-terminal acetylation of annexin A2 is required for S100A10 binding. Biol Chem 393:1141-50
Arai, Hiromi; Glabe, Charles; Luecke, Hartmut (2012) Crystal structure of a conformation-dependent rabbit IgG Fab specific for amyloid prefibrillar oligomers. Biochim Biophys Acta 1820:1908-14
Scott, David R; Marcus, Elizabeth A; Wen, Yi et al. (2010) Cytoplasmic histidine kinase (HP0244)-regulated assembly of urease with UreI, a channel for urea and its metabolites, CO2, NH3, and NH4(+), is necessary for acid survival of Helicobacter pylori. J Bacteriol 192:94-103