title: Cys-Cys cross-linking shows contact between the N-terminus of lethal factor and Phe427 of the anthrax toxin pore.
abstract: Electrophysiological studies of wild-type and mutated forms of anthrax protective antigen (PA) suggest that the Phe clamp, a structure formed by the Phe427 residues within the lumen of the oligomeric PA pore, binds the unstructured N-terminus of the lethal factor and the edema factor during initiation of translocation. We now show by electrophysiological measurements and gel shift assays that a single Cys introduced into the Phe clamp can form a disulfide bond with a Cys placed at the N-terminus of the isolated N-terminal domain of LF. These results demonstrate direct contact of these Cys residues, supporting a model in which the interaction of the unstructured N-terminus of the translocated moieties with the Phe clamp initiates N- to C-terminal threading of these moieties through the pore.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States.
authors.forename: Blythe E
authors.initials: BE
authors.lastname: Janowiak
authors.forename: Laura D
authors.initials: LD
authors.lastname: Jennings-Antipov
authors.forename: R John
authors.initials: RJ
authors.lastname: Collier
mesh_terms: D000942:Antigens, Bacterial / Q000737:chemistry* / Q000235:genetics; D001408:Bacillus anthracis; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics; D003432:Cross-Linking Reagents / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry; D024202:Electrophoretic Mobility Shift Assay; D008051:Lipid Bilayers; D008564:Membrane Potentials; D009154:Mutation; D010649:Phenylalanine / Q000737:chemistry*; D055503:Protein Multimerization; D021381:Protein Transport
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D003432:Cross-Linking Reagents; D004220:Disulfides; D008051:Lipid Bilayers; C030325:anthrax toxin; D010649:Phenylalanine; D003545:Cysteine