title: The CagA toxin of Helicobacter pylori: abundant production but relatively low amount translocated.
abstract: CagA is one of the most studied pathogenicity factors of the bacterial pathogen Helicobacter pylori. It is injected into host cells via the H. pylori cag-Type IV secretion system. Due to its association with gastric cancer, CagA is classified as oncogenic protein. At the same time CagA represents the 4(th) most abundant protein produced by H. pylori, suggesting that high amounts of toxin are required to cause the physiological changes or damage observed in cells. We were able to quantify the injection of CagA into gastric AGS epithelial cells in vitro by the adaptation of a novel protease-based approach to remove the tightly adherent extracellular bacteria. After one hour of infection only 1.5% of the total CagA available was injected by the adherent bacteria, whereas after 3 hours 7.5% was found within the host cell. Thus, our data show that only a surprisingly small amount of the CagA available in the infection is finally injected under in vitro infection conditions.
authors.affiliation: Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität, Pettenkoferstraße 9a, D-80336 München, Germany.
authors.forename: Luisa F
authors.initials: LF
authors.lastname: Jiménez-Soto
authors.affiliation: Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität, Pettenkoferstraße 9a, D-80336 München, Germany.|German Center for Infection Research (DZIF), LMU Munich, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Haas
mesh_terms: D000942:Antigens, Bacterial / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D019286:Endopeptidase K / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D016480:Helicobacter pylori / Q000378:metabolism*; D006801:Humans; D010766:Phosphorylation; D019030:Receptors, Vitronectin / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D019030:Receptors, Vitronectin; C080866:cagA protein, Helicobacter pylori; C094340:integrin alphavbeta1; D019286:Endopeptidase K