title: A novel DNA-binding protein plays an important role in Helicobacter pylori stress tolerance and survival in the host.
abstract: The gastric pathogen Helicobacter pylori must combat chronic acid and oxidative stress. It does so via many mechanisms, including macromolecule repair and gene regulation. Mitomycin C-sensitive clones from a transposon mutagenesis library were screened. One sensitive strain contained the insertion element at the locus of hp119, a hypothetical gene. No homologous gene exists in any (non-H. pylori) organism. Nevertheless, the predicted protein has some features characteristic of histone-like proteins, and we showed that purified HP119 protein is a DNA-binding protein. A Δhp119 strain was markedly more sensitive (viability loss) to acid or to air exposure, and these phenotypes were restored to wild-type (WT) attributes upon complementation of the mutant with the wild-type version of hp119 at a separate chromosomal locus. The mutant strain was approximately 10-fold more sensitive to macrophage-mediated killing than the parent or the complemented strain. Of 12 mice inoculated with the wild type, all contained H. pylori, whereas 5 of 12 mice contained the mutant strain; the mean colonization numbers were 158-fold less for the mutant strain. A proteomic (two-dimensional PAGE with mass spectrometric analysis) comparison between the Δhp119 mutant and the WT strain under oxidative stress conditions revealed a number of important antioxidant protein differences; SodB, Tpx, TrxR, and NapA, as well as the peptidoglycan deacetylase PgdA, were significantly less expressed in the Δhp119 mutant than in the WT strain. This study identified HP119 as a putative histone-like DNA-binding protein and showed that it plays an important role in Helicobacter pylori stress tolerance and survival in the host.
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA.
authors.forename: Ge
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA rmaier@uga.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Maier
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016481:Helicobacter Infections / Q000378:metabolism / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D050296:Microbial Viability; D018384:Oxidative Stress
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins