Inhibitors of Helicobacter pylori Protease HtrA Found by ‘Virtual Ligand’ Screening Combat Bacterial Invasion of Epithelia

Abstract

BackgroundThe human pathogen Helicobacter pylori (H. pylori) is a main cause for gastric inflammation and cancer. Increasing bacterial resistance against antibiotics demands for innovative strategies for therapeutic intervention.Methodology/Principal FindingsWe present a method for structure-based virtual screening that is based on the comprehensive prediction of ligand binding sites on a protein model and automated construction of a ligand-receptor interaction map. Pharmacophoric features of the map are clustered and transformed in a correlation vector (‘virtual ligand’) for rapid virtual screening of compound databases. This computer-based technique was validated for 18 different targets of pharmaceutical interest in a retrospective screening experiment. Prospective screening for inhibitory agents was performed for the protease HtrA from the human pathogen H. pylori using a homology model of the target protein. Among 22 tested compounds six block E-cadherin cleavage by HtrA in vitro and result in reduced scattering and wound healing of gastric epithelial cells, thereby preventing bacterial infiltration of the epithelium.Conclusions/SignificanceThis study demonstrates that receptor-based virtual screening with a permissive (‘fuzzy’) pharmacophore model can help identify small bioactive agents for combating bacterial infection.

Distinct Roles of Secreted HtrA Proteases from Gram-negative Pathogens in Cleaving the Junctional Protein and Tumor Suppressor E-cadherin

“…We have developed the inhibitor HHI for HpHtrA (15) that impaired E-cadherin degradation and epithelial barrier (4). On the basis of our data, we concluded that specific inhibition of HtrAs from different pathogens requires highly selective compounds.…”

“…We described the first functional inhibitor HHI targeting HpHtrA (15) to prevent E-cadherin shedding and the paracellular transmigration of H. pylori (4). To test whether HHI also inhibits HtrA from other Gram-negative bacteria, we performed in vitro E-cadherin cleavage experiments (Fig.…”

Bacterial proteolytic complexes as therapeutic targets

“…Thus, given the crucial role of HtrA in virulence in numerous pathogenic organisms, this protease is an attractive target for antibiotic development. Using structure-based virtual screening, Lower et al 99 found a set of compounds that had the potential to act as small-molecule inhibitors of H. pylori HtrA, the enzyme that cleaves host E-cadherins. Out of the 22 compounds retrieved from virtual screening, 6 were shown to inhibit cleavage of E-cadherins by H. pylori HtrA in an in vitro proteolysis assay.…”

A role for altered phagosome maturation in the long-term persistence ofHelicobacter pyloriinfection

“…Previously, proteolytic cleavage of E-cadherin was linked to the malignant progression of adenocarcinomas (35,44). By using a virtual screening approach, Lower et al (91) identified inhibitors of HtrA that may help prevent bacterial infiltration of the epithelium.…”