title: Precise localization of an overproduced periplasmic protein in Escherichia coli: use of double immuno-gold labelling.
abstract: The subcellular localization of beta-lactamase produced by a secretion-cloning vector pIN-III was studied by immunolabelling of frozen thin sections of Escherichia coli. Using double immuno-gold detections and internal reference proteins, it is shown here that beta-lactamase encoded by this vector can be exported and that its overproduction leads to aggregation within the periplasm. This aggregation induces the appearance of electron-dense areas immunolabelled by the antiserum directed against the beta-lactamase at the external side of the cytoplasmic membrane. The overproduced enzyme is also secreted to the medium in vesicles budding from the outer membrane of lpp strains.
authors.affiliation: Centre de Biochimie et de Biologie Moléculaire du C.N.R.S., Marseille, France.
authors.forename: A
authors.initials: A
authors.lastname: Bernadac
authors.forename: J M
authors.initials: JM
authors.lastname: Bolla
authors.forename: C
authors.initials: C
authors.lastname: Lazdunski
authors.forename: M
authors.initials: M
authors.lastname: Inouye
authors.forename: J M
authors.initials: JM
authors.lastname: Pages
mesh_terms: D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D005822:Genetic Vectors; D006046:Gold; D007106:Immune Sera; D007118:Immunoassay; D008854:Microscopy, Electron; D010957:Plasmids; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D007106:Immune Sera; D006046:Gold; D001618:beta-Lactamases