M. Debernard et al., LOW PH ACTIVATES THE VACUOLATING TOXIN OF HELICOBACTER-PYLORI, WHICH BECOMES ACID AND PEPSIN RESISTANT, The Journal of biological chemistry, 270(41), 1995, pp. 23937-23940
The protein toxin VacA, produced by cytotoxic strains of Helicobacter
pylori, causes a vacuolar degeneration of cells, which eventually die.
VacA is strongly activated by a short exposure to acidic solutions in
the pH 1.5-5.5 range, followed by neutralization. Activated VacA has
different CD and fluorescence spectra and a limited proteolysis fragme
ntation pattern from VacA kept at neutral pH. Moreover, activated VacA
is resistant to pH 1.5 and to pepsin. The relevance of these findings
to pathogenesis of H. pylori-induced gastrointestinal ulcers is discu
ssed.