Cell-cycle inhibition by Helicobacter pylori L-asparaginase

PLoS One. 2010 Nov 9;5(11):e13892. doi: 10.1371/journal.pone.0013892.

Abstract

Helicobacter pylori (H. pylori) is a major human pathogen causing chronic gastritis, peptic ulcer, gastric cancer, and mucosa-associated lymphoid tissue lymphoma. One of the mechanisms whereby it induces damage depends on its interference with proliferation of host tissues. We here describe the discovery of a novel bacterial factor able to inhibit the cell-cycle of exposed cells, both of gastric and non-gastric origin. An integrated approach was adopted to isolate and characterise the molecule from the bacterial culture filtrate produced in a protein-free medium: size-exclusion chromatography, non-reducing gel electrophoresis, mass spectrometry, mutant analysis, recombinant protein expression and enzymatic assays. L-asparaginase was identified as the factor responsible for cell-cycle inhibition of fibroblasts and gastric cell lines. Its effect on cell-cycle was confirmed by inhibitors, a knockout strain and the action of recombinant L-asparaginase on cell lines. Interference with cell-cycle in vitro depended on cell genotype and was related to the expression levels of the concurrent enzyme asparagine synthetase. Bacterial subcellular distribution of L-asparaginase was also analysed along with its immunogenicity. H. pylori L-asparaginase is a novel antigen that functions as a cell-cycle inhibitor of fibroblasts and gastric cell lines. We give evidence supporting a role in the pathogenesis of H. pylori-related diseases and discuss its potential diagnostic application.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminolevulinic Acid / analogs & derivatives
  • Aminolevulinic Acid / pharmacology
  • Animals
  • Asparaginase / genetics
  • Asparaginase / metabolism*
  • Asparaginase / pharmacology
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Bacterial Proteins / pharmacology
  • Biocatalysis / drug effects
  • Cell Cycle / drug effects
  • Cell Cycle / physiology*
  • Cell Line, Tumor
  • Cells, Cultured
  • Enzyme-Linked Immunosorbent Assay
  • Fibroblasts / cytology
  • Fibroblasts / drug effects
  • Helicobacter pylori / enzymology*
  • Helicobacter pylori / genetics
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Mutation

Substances

  • Bacterial Proteins
  • 5-diazo-4-oxonorvaline
  • Aminolevulinic Acid
  • Asparaginase