Mutation of cytotoxin-associated gene A affects expressions of antioxidant proteins of Helicobacter pylori

Abstract

AIM:To determine if disruption of the cagA gene of Helicobacter pylori (H pylori ) has an effect on the expression of other proteins at proteome level.METHODS: C o n s t r u c t i o n o f a cagA k n o c k o u t m u t a n t H p 2 7 _ ∆c a g A (c a g A -) v i a h o m o l o g o u s re c o m b i n a t i o n w i t h t h e w i l d -ty p e s t ra i n Hp27 (cagA + ) as a recipient was performed. The method o f s o n i c a t i o n -u r e a -C H A P S -DTT wa s e m p l o ye d to extract bacterial proteins from both strains. Soluble proteins were analyzed by two-dimensional electrophoresis (2-DE). Images of 2-DE gels were digitalized and analyzed. Only spots that had a statistical significance in differential expression were selected and analyzed by matrix-assisted laser desorption/ionizationtime of flight mass spectrometry (MALDI-TOF-MS). Biological information was used to search protein database and identify the biological function of proteins. RESULTS:The proteome expressions between wild-type strain and isogenic mutant with the cagA gene knocked-out were compared. Five protein spots with high abundance in bacteria proteins of wild-type strains, down-regulated or absently expressed in bacteria proteins of mutants, were identified and analyzed. From a quantitative point of view, the identified proteins are related to the cagA gene and important antioxidant proteins of H pylori , including alkyl hydroperoxide reductase (Ahp), superoxide dismutase (SOD) and modulator of drug activity (Mda66), respectively, suggesting that cagA is important to maintain the normal activity of antioxidative stress and ensure H pylori persistent colonization in the host. C O N C L U S I O N :c a g A g e n e i s r e l e v a n t t o t h e expressions of antioxidant proteins of H pylori , which may be a novel mechanism involved in H pylori cagA pathogenesis.

Antigenic Diversity Among Portuguese Clinical Isolates of Helicobacter pylori

“…3B). Supporting our data, Huang Z. G. et al reported lower expression levels of AhpC in cagA mutant strains [43].…”

Superoxide dismutase activity of Helicobacter pylori per se from 158 clinical isolates and the characteristics

“…Interestingly, only HPK5CA2, cagA ‐disruptant, showed different electrophoretic migration and the SOD activity of HPK5CA2 decreased to 55% of that of HPK5 (data not shown), indicating that CagA affects modification of Fe‐SOD and loss of CagA is responsible for the reduced SOD activity. It was reported that a knock‐out of cagA was responsible for down‐regulation of antioxidant proteins, including SOD and alkyl hydroperoxide reductase (56). Although the mechanism was still unknown, the authors suggested that cagA might be related to a ferric uptake regulator (Fur) and/or a post‐transcriptional regulator CsrA (24), through which cagA influences the expression of antioxidant proteins (56).…”

“…It was reported that a knock‐out of cagA was responsible for down‐regulation of antioxidant proteins, including SOD and alkyl hydroperoxide reductase (56). Although the mechanism was still unknown, the authors suggested that cagA might be related to a ferric uptake regulator (Fur) and/or a post‐transcriptional regulator CsrA (24), through which cagA influences the expression of antioxidant proteins (56). Regarding antioxidant systems of H. pylori , many proteins are involved in the diverse antioxidant systems and an iron sequestering protein has dual roles, such as host inflammation stimulation and minimizing ROS (24).…”

Helicobacter pylori cagA Gene Polymorphism Affects the Total Antioxidant Capacity of Human Saliva

“…It was shown that infection with cagA+ H. pylori strains was correlated with a massive increase in oxidative DNA damage of host cells compared to cagA‐ H. pylori infection [14]. Moreover, cagA gene was found important to maintain antioxidative defense of H. pylori since knock‐out of cagA gene was responsible for downregulation of superoxide dismutase or alkyl hydroperoxide reductase which may be a novel mechanism implicated in H. pylori pathogenesis [15]. Additionally, the level of reduced glutathione (GSH) was significantly lower in H. pylori ‐infected patients than in H. pylori ‐free subjects [16], which in turn may be associated with gastric carcinogenesis [17].…”