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.

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.

3D imaging of the 58 kDa cell binding subunit of the Helicobacter pylori cytotoxin

LUPETTI, PIETRO;ULIVIERI, CRISTINA;
1999-01-01

Abstract

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.
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.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/21919
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