Analysis of Methionine Oxidation and Repair in Heliobacter pylori

摘要

Heliobacter pylori is a bacterium that infects the lining of the stomach, and is the leading cause of gastric ulcers and some forms of stomach cancer. Upon infection of the stomach lining, activated neutrophils release reactive oxygen/nitrogen species including hypochlorous acid, which converts methionine residues to methionine sulfoxide. To combat oxidative antibacterial defenses, H. pylori expresses a methionine sulfoxide reductase (Msr), which converts methionine sulfoxide to methionine. Msr interacts with proteins involved in allowing the bacterium to persist in the hostile environment of the stomach, including the antioxidant protein catalase and the urease accessory protein UreG. Here, we quantify the HOCl-mediated oxidation and Msr-based repair in catalase and using LC coupled to mass spectrometry with a pseudo-MRM strategy. We also show initial results from quantifying H_(2)O_(2)-mediated oxidation and repair of UreG by a pseudo-MRM strategy coupled with UPLC separation.