Structure and interaction of VacA of Helicobacter pylori with a lipid membrane.
Eur J Biochem
; 267(1): 104-9, 2000 Jan.
Article
em En
| MEDLINE
| ID: mdl-10601856
ABSTRACT
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.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Helicobacter pylori
/
Bicamadas Lipídicas
Idioma:
En
Ano de publicação:
2000
Tipo de documento:
Article