Identification of S-nitrosylation of proteins of Helicobacter pylori in response to nitric oxide stress

Abstract

Innate and adaptive immune responses are activated in humans when Helicobacter pylori invades the gastric mucosa. Nitric oxide (NO) and reactive nitrogen species are important immune effectors, which can exert their functions through oxidation and S-nitrosylation of proteins. S-nitrosoglutathione and sodium nitroprus-side were used as NO donors and H. pylori cells were incubated with these compounds to analyze the inhibitory effect of NO. The suppressing effect of NO on H. pylori has been shown in vitro. Furthermore, the proteins modified by S-nitrosylation in H. pylori were identified through the biotin switch method in association with matrix-assisted laser desorption ionization/time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS). Five S-nitrosylated proteins identified were a chaperone and heat-shock protein (GroEL), alkyl hydroperoxide reductase (TsaA), urease alpha subunit (UreA), HP0721, and HP0129. Importantly, S-nitrosylation of TsaA and UreA were confirmed using purified recombinant proteins. Considering the importance of these enzymes in antioxidant defenses, adherence, and colonization, NO may exert its antibacterial actions by targeting enzymes through S-nitrosylation. Identification of protein S-nitrosylation may contribute to an understanding of the antibacterial actions of NO. Our findings provide an insight into potential targets for the development of novel therapeutic agents against H. pylori infection.

Expression of three essential antioxidants of Helicobacter pylori in clinical isolates

“…The inflammatory host response can not only lead to gastric cancer, but also threaten the survival of H. pylori. The suppressing effect of oxidative stress species has also been reported in vitro (Qu et al, 2011). Nevertheless, H. pylori successfully survives these conditions and persistently colonizes the gastric mucosa.…”

Nitrosothiols in Bacterial Pathogens and Pathogenesis

“…Five proteins of Helicobacter pylori were recently identified as SNO-proteins, following exposure of bacterial lysates, produced from microaerobic cultures, to 100 lM GSNO and through use of the BST (91). These include alkyl hydroperoxide reductase (TsaA) and the urease alpha subunit (UreA), 6 LAVER ET AL.…”

“…the latter being reversibly inhibited by GSNO in a concentration-dependent manner (91). S-nitrosylation of a number of proteins from Borrelia burgdorferi has been implicated in the susceptibility of this bacterium to killing by NO (13).…”

Oxidative and nitrosative stress defences ofHelicobacterandCampylobacterspecies that counteract mammalian immunity

“…Another proteomic study of H. pylori treated with GSNO (100 μM for 20 min) detected five differentially expressed proteins including the chaperone and heat shock protein (GroEL), urease alpha subunit (UreA), alkyl hydroperoxide reductase (designated as TsaA), sialic acid-specific adhesion protein HP0721 and a protein of unknown function HP0129 (Qu et al 2011). Consistent with these results, deletion of tsaA in H. pylori increased the sensitivity of the bacterium to RNS.…”