Comparison of Gene Expression Patterns between Helicobacter pylor 26695 and its Superoxide Dismutase Isogenic Mutant

ABSTRACT

Helicobacter pylori, a causative agent of gastroduodenal diseases, is a Gram-negative microaerophilic bacterium. Although H. pylori locates in the microaerophilic mucous layer, the bacteria would come into contact harmful reactive oxygen species generated by host immune system. It has been reported that H. pylori harbors various defense mechanisms which can protect bacterial cells from oxygen exposure. The change of the gene expression profile of sodB-negative isogenic mutant of H. pylori 26695 was analyzed by high resolution 2-DE followed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem MS and microarray analysis. Eighteen genes and 41 genes were upregulated and downregulated respectively, either transcriptionally or translationally. Expression levels of three genes including trxB, yxjE and ribE that were changed both on a mRNA level and on a protein level were confirmed by RT-PCR analysis. However, change of expression levels of other major antioxidants such as KatA, AhpC and NapA were not detected, which means Sod is regulated by different way from that of KatA and AhpC. Mutant study of other antioxidant proteins may give us better understanding for the regulation of stress response in H. pylori.