The effect of nitrosative and oxidative stress on Helicobacter pylori
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The gastric pathogen Helicobacter pylori is able to withstand an onslaught of oxidative and nitrosative stress from the host immune system. One such stress arises from protein tyrosine nitration by peroxynitrite (ONOO-), which is a product of superoxide and nitric oxide released from macrophages. We utilized a proteomics-based approach, combining anti-nitrotyrosine antibody western blots and MALDI-TOF analysis, to identify targets of nitration within H. pylori. Through this approach, we have identified several target proteins. Most of the identified proteins are predicted to localize either to the periplasm or associate with the membrane. Further studies on purified catalase showed its activity decreases in a peroxynitrite dose-dependent manner, with a concomitant increase in tyrosine nitration. An additional study was conducted to understand the role of protein L-isoaspartate methyltransferase in H. pylori physiology. By immunoblot analysis, we have begun to describe how and where this protein is expressed in H. pylori.