Pathogenic strains of Helicobacter pylori produce a potent exotoxin, VacA, which intoxicates gastric epithelial cells and leads to peptic ulcer. The toxin is released from the bacteria as a high molecular mass homo-oligo- mer of a 95 kDa polypeptide which undergoes speci®c proteolytic cleavage to 37 kDa and 58 kDa subunits. We have engineered a strain of H. pylori to delete the gene sequence coding for the 37 kDa subunit. The remaining 58 kDa subunit is expressed ef®ciently and exported as a soluble dimer that is non-toxic but binds target cells in a manner similar to the holotoxin. A 3D reconstruction of the molecule from electron micrographs of quick-freeze, deep-etched preparations reveals the contri- bution of each building block to the structure and permits the reconstruc- tion of the oligomeric holotoxin starting from individual subunits. In this model P58 subunits are assembled in a ring structure with P37 subunits laying on the top. The data indicate that the 58 kDa subunit is capable of folding autonomously into a discrete structure recognizable within the holotoxin and containing the cell binding domain.
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|Titolo:||3D imaging of the 58 kDa cell binding subunit of the Helicobacter pylori cytotoxin|
|Rivista:||JOURNAL OF MOLECULAR BIOLOGY|
|Citazione:||Reyrat, J.m., Lanzavecchia, S., Lupetti, P., DE BERNARD, M., Pagliaccia, C., Pelicic, V., et al. (1999). 3D imaging of the 58 kDa cell binding subunit of the Helicobacter pylori cytotoxin. JOURNAL OF MOLECULAR BIOLOGY, 290, 459-470.|
|Appare nelle tipologie:||1.1 Articolo in rivista|