title: Cag-delta (Cag3) protein from the Helicobacter pylori 26695 cag type IV secretion system forms ring-like supramolecular assemblies.
abstract: Helicobacter pylori is an important cause of gastric pathologies and persistent infection can lead to stomach cancer. Virulent H. pylori strains encode a type IV secretion system responsible for translocation of the oncogenic CagA protein into cells of the gastric mucosa. Gene HP0522 encodes the essential component Cagδ (Cag3), and we show by gel filtration and cross-linking that purified Cagδ forms high molecular mass complexes. In contrast, its interaction partner CagT is mostly monomeric, but co-fractionates after gel filtration. Analysis by transmission electron microscopy revealed that purified Cagδ complexes can self-assemble ring-like structures. Cagδ-overexpressing Escherichia coli exhibits membrane-associated circular profiles in regions of the cell envelope with intense immunogold labelling with a Cagδ-specific antiserum. Our results suggest that Cagδ has the capacity to form macromolecular structures contributing to the assembly of the type IV secretion system.
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montreal, QC H3C 3J7, Canada.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Smart
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montreal, QC H3C 3J7, Canada.|Laboratory for the Study of Calcified Tissues and Biomaterials, Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montreal, QC H3C 3J7, Canada.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Fouillen
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montreal, QC H3C 3J7, Canada.
authors.forename: Bastien
authors.initials: B
authors.lastname: Casu
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montreal, QC H3C 3J7, Canada.|Laboratory for the Study of Calcified Tissues and Biomaterials, Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montreal, QC H3C 3J7, Canada.
authors.forename: Antonio
authors.initials: A
authors.lastname: Nanci
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montreal, QC H3C 3J7, Canada christian.baron@umontreal.ca.
authors.forename: Christian
authors.initials: C
authors.lastname: Baron
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D002850:Chromatography, Gel; D002942:Circular Dichroism; D005753:Gastric Mucosa / Q000382:microbiology; D016480:Helicobacter pylori / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D046911:Macromolecular Substances; D046529:Microscopy, Electron, Transmission; D011485:Protein Binding; D000069319:Type IV Secretion Systems / Q000737:chemistry* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D046911:Macromolecular Substances; D000069319:Type IV Secretion Systems
keywords: Helicobacter; electron microscopy; type IV secretion system; virulence