High resolution structural analysis of Helicobacter pylori VacA toxin oligomers by cryo-negative staining electron microscopy.

Détails

ID Serval
serval:BIB_060CF6A81B88
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
High resolution structural analysis of Helicobacter pylori VacA toxin oligomers by cryo-negative staining electron microscopy.
Périodique
Journal of Structural Biology
Auteur(s)
El-Bez C., Adrian M., Dubochet J., Cover T.L.
ISSN
1047-8477
Statut éditorial
Publié
Date de publication
09/2005
Peer-reviewed
Oui
Volume
151
Numéro
3
Pages
215-228
Langue
anglais
Notes
Journal Article Research Support, N.I.H., Extramural Research Support, U.S. Gov't, Non-P.H.S. Research Support, U.S. Gov't, P.H.S. --- Old month value: Sep
Résumé
Helicobacter pylori secretes a vacuolating toxin (VacA) that can assemble into water-soluble oligomeric complexes and insert into membranes to form anion-selective channels. Previous studies have described multiple types of oligomeric VacA structures, including single-layered astral arrays, bilayered forms, and two-dimensional crystalline arrays. In the current study, vitrified VacA complexes were examined by cryo-negative staining electron microscopy, views of the different oligomeric structures in multiple orientations were classified and analyzed, and three-dimensional models of the bilayered forms of VacA were constructed with a resolution of about 19 angstroms. These bilayered forms of VacA have a "flower"-like structure, consisting of a central ring surrounded by symmetrically arranged peripheral "petals." Further structural insights were obtained by analyzing a mutant form of VacA (VacADelta6-27), which lacks a unique amino-terminal hydrophobic segment and is defective in the capacity to form membrane channels. Bilayered oligomeric complexes formed by wild-type VacA contained a visible density within the central ring, whereas bilayered complexes formed by VacADelta6-27 lacked this density. These results indicate that deletion of the VacA amino-terminal hydrophobic region causes a structural alteration in the central ring within VacA oligomers, and suggest that the central ring plays an important role in the process by which VacA forms membrane channels.
Mots-clé
Bacterial Proteins, Cryoelectron Microscopy, Helicobacter pylori, Imaging, Three-Dimensional, Mutation, Negative Staining
Pubmed
Web of science
Création de la notice
24/01/2008 11:25
Dernière modification de la notice
20/08/2019 13:28
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