Open AccessStructure and interaction of VacA of Helicobacter pylori with a lipid membrane
Author(s) -
Pagliaccia Cristina,
Wang XiaoMing,
Tardy Florence,
Telford John L.,
Ruysschaert JeanMarie,
Cabiaux Véronique
Publication year - 2000
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2000.00970.x
Subject(s) - vesicle , chemistry , calcein , lipid bilayer , membrane , biophysics , biochemistry , biology
In its mature form, the VacA toxin of Helicobacter pylori is a 95‐kDa protein which is released from the bacteria as a low‐activity complex. This complex can be activated by low‐pH treatment that parallels the activity of the toxin on target cells. VacA has been previously shown to insert itself into lipid membranes and to induce anion‐selective channels in planar lipid bilayers. Binding of VacA to lipid vesicles and its ability to induce calcein release from these vesicles were systematically compared as a function of pH. These two phenomena show a different pH‐dependence, suggesting that the association with the lipid membrane may be a two‐step mechanism. The secondary and tertiary structure of VacA as a function of pH and the presence of lipid vesicles were investigated by Fourier‐transform infrared spectroscopy. The secondary structure of VacA is identical whatever the pH and the presence of a lipid membrane, but the tertiary structure in the presence of a lipid membrane is dependent on pH, as evidenced by H/D exchange.