title: Cell-cycle inhibition by Helicobacter pylori L-asparaginase.
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.
authors.affiliation: Department of Experimental Medicine, Section of General Pathology, University of Pavia, Pavia, Italy. claudia.scotti@unipv.it
authors.forename: Claudia
authors.initials: C
authors.lastname: Scotti
authors.forename: Patrizia
authors.initials: P
authors.lastname: Sommi
authors.forename: Maria Valentina
authors.initials: MV
authors.lastname: Pasquetto
authors.forename: Donata
authors.initials: D
authors.lastname: Cappelletti
authors.forename: Simona
authors.initials: S
authors.lastname: Stivala
authors.forename: Paola
authors.initials: P
authors.lastname: Mignosi
authors.forename: Monica
authors.initials: M
authors.lastname: Savio
authors.forename: Laurent Roberto
authors.initials: LR
authors.lastname: Chiarelli
authors.forename: Giovanna
authors.initials: G
authors.lastname: Valentini
authors.forename: Victor M
authors.initials: VM
authors.lastname: Bolanos-Garcia
authors.forename: Douglas Scott
authors.initials: DS
authors.lastname: Merrell
authors.forename: Silvia
authors.initials: S
authors.lastname: Franchini
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Verona
authors.forename: Cristina
authors.initials: C
authors.lastname: Bolis
authors.forename: Enrico
authors.initials: E
authors.lastname: Solcia
authors.forename: Rachele
authors.initials: R
authors.lastname: Manca
authors.forename: Diego
authors.initials: D
authors.lastname: Franciotta
authors.forename: Andrea
authors.initials: A
authors.lastname: Casasco
authors.forename: Paola
authors.initials: P
authors.lastname: Filipazzi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Zardini
authors.forename: Vanio
authors.initials: V
authors.lastname: Vannini
mesh_terms: D000622:Aminolevulinic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001215:Asparaginase / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D055162:Biocatalysis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation
chemical_list: D001426:Bacterial Proteins; C002199:5-diazo-4-oxonorvaline; D000622:Aminolevulinic Acid; D001215:Asparaginase