Disease-associated strains of Helicobacter pylori produce a potent toxin that is believed to play a key role in peptic ulcer disease in man. In vitro the toxin causes severe vacuolar degeneration in target cells and has thus been termed VacA (for vacuolating c_.ytotoxin A). Cytotoxic activity is associated with a >600-kD protein consisting of several copies of a 95- kD polypeptide that undergoes specific proteolytic cleavage after release from the bacteria to produce 37- and 58-kD fragments. Quick freeze, deep etch electron microscopy has revealed that the native cytotoxin is formed as regular oligomers with either six- or sevenfold radial symmetry. Within each monomer, two domains can clearly be distinguished, suggesting that the 37- and 58-kD fragments derive from proteolytic cleavage between discrete subunits of the monomer. Analysis of preparations of the toxin that had undergone extensive cleavage into the 37- and 58-kD subunits supports this interpretation and reveals that after cleavage the subunits remain associated in the oligomeric structure. The data suggest a structural similarity with AB-type toxins.
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|Titolo:||Oligomeric and subunit structure of the Helicobacter pylori vacuolating cytotoxin|
|Citazione:||Lupetti, P., Heuser, J.E., Manetti, R., Massari, P., Lanzavecchia, S., Bellon, P.L., et al. (1996). Oligomeric and subunit structure of the Helicobacter pylori vacuolating cytotoxin. THE JOURNAL OF CELL BIOLOGY, 133(4), 801-807.|
|Appare nelle tipologie:||1.1 Articolo in rivista|