title: Export of virulence genes and Shiga toxin by membrane vesicles of Escherichia coli O157:H7.
abstract: Membrane vesicles released by Escherichia coli O157:H7 into culture medium were purified and analyzed for protein and DNA content. Electron micrographs revealed vesicles that are spherical, range in size from 20 to 100 nm, and have a complete bilayer. Analysis of vesicle protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrates vesicles that contain many proteins with molecular sizes similar to outer membrane proteins and a number of cellular proteins. Immunoblot (Western) analysis of vesicles suggests the presence of cell antigens. Treatment of vesicles with exogenous DNase hydrolyzed surface-associated DNA; PCR demonstrated that vesicles contain DNA encoding the virulence genes eae, stx1 and stx2, and uidA, which encodes for beta-galactosidase. Immunoblot analysis of intact and lysed, proteinase K-treated vesicles demonstrate that Shiga toxins 1 and 2 are contained within vesicles. These results suggest that vesicles contain toxic material and transfer experiments demonstrate that vesicles can deliver genetic material to other gram-negative organisms.
authors.affiliation: Department of Food Science, Rutgers University, New Brunswick, New Jersey 08901, USA.
authors.forename: G L
authors.initials: GL
authors.lastname: Kolling
authors.forename: K R
authors.initials: KR
authors.lastname: Matthews
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001427:Bacterial Toxins / Q000378:metabolism*; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D019453:Escherichia coli O157 / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D018014:Gene Transfer Techniques; D005798:Genes, Bacterial; D008854:Microscopy, Electron; D022603:Shiga Toxins; D014774:Virulence / Q000235:genetics
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001427:Bacterial Toxins; D017931:DNA Primers; D004269:DNA, Bacterial; D022603:Shiga Toxins