Investigating the pH gating mechanism of Helicobacter pyloris UreI

Description

Chronic gastric infections with Helicobacter pylori are present in over 50% of the world population and are linked to diseases like peptic ulcer and stomach cancer. The commonly used antibiotic therapy is getting less efficient due to increasing antibiotic resistance. An alternative drug target could be the pH-gated inner membrane urea channel UreI which is crucial for the survival of the bacteria in the acidic environment of the human stomach. However, despite in vivo studies and high-resolution structures in the open and closed state, HpUreIs gating mechanism is still elusive. To gain molecular insight into its gating mechanism we also tested the homologous urea channel from Streptococcus salivarius using yeast complementation assays. Relative urea and ammonia permeabilities are compared to the wild-type protein in the physiologically relevant pH range of 4.0 - 7.0. The results question the hypothesis of PL1 and PL2 constituting the main pH-sensor of HpUreI as the urea channel from S. salivarius, lacking such extensive periplasmic loops, shows similar pH-dependence as HpUreI. These results could be verified for overexpressed, purified and reconstituted SsUreI in in vitro measurements. Our experimental studies are guided and accompanied by an extensive sequence- and structure-based analysis of homologous bacterial urea channels, which spot interesting sub-group variants and conserved protein features as well as positions. Yeast complementation assays constitute a cost-effective tool for testing such qualitative differences in protein variant activity for a broad range of solutes.

Period	10 Jul 2024
Event title	Biophysics Austria biennial conference
Event type	Conference
Location	Salzburg, AustriaShow on map
Degree of Recognition	National