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World J Gastroenterol. Feb 7, 2009; 15(5): 599-606
Published online Feb 7, 2009. doi: 10.3748/wjg.15.599
Mutation of cytotoxin-associated gene A affects expressions of antioxidant proteins of Helicobacter pylori
Zhi-Gang Huang, Guang-Cai Duan, Qing-Tang Fan, Wei-Dong Zhang, Chun-Hua Song, Xue-Yong Huang, Rong-Guang Zhang
Zhi-Gang Huang, Guang-Cai Duan, Qing-Tang Fan, Wei-Dong Zhang, Chun-Hua Song, Xue-Yong Huang, Rong-Guang Zhang, Department of Epidemiology, College of Public Health, Zhengzhou University, Zhengzhou 450001, Henan Province, China
Zhi-Gang Huang, Department of Epidemiology, School of Public Health, Guangdong Medical College, Dongguan 523808, Guangdong Province, China
Author contributions: Huang ZG performed the research and wrote the paper; Duan GC designed the research and revised the paper; Fan QT contributed to new analytic tools; Zhang WD, Song CH revised the paper; Huang XY, Zhang RG analyzed the data.
Correspondence to: Guang-Cai Duan, Department of Epidemiology, College of Public Health, Zhengzhou University, Zhengzhou 450001, Henan Province, China. gcduan@public.zz.ha.cn
Telephone: +86-371-66940316
Fax: +86-371-66997182
Received: July 25, 2008
Revised: December 3, 2008
Accepted: December 10, 2008
Published online: February 7, 2009
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: Construction of a cagA knock out mutant Hp27_ΔcagA (cagA-) via homologous recombination with the wild-type strain Hp27 (cagA+) as a recipient was performed. The method of sonication-urea-CHAPS-DTT was employed 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/ionization-time 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.

CONCLUSION: cagA gene is relevant to the expressions of antioxidant proteins of H pylori, which may be a novel mechanism involved in H pylori cagA pathogenesis.

Keywords: Helicobacter pylori; Cytotoxin-associated gene A; Knock-out; Antioxidant protein; Two-dimensional electrophoresis