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In this paper we study the assembly, in vivo and in vitro, of a family of hexameric, heat-labile enterotoxins produced by diarrheagenic bacteria. The toxins, which consist of an A subunit and five B subunits, are assembled by a highly coordinated process that ensures secretion of the holotoxin complex. We show that (i) oxidation of cysteine residues in the(More)
Common variable immunodeficiency (CVID) is a primary immune disorder characterized by impaired antibody production, which is in many instances secondary to defective T-cell function (T-CVID). We have previously identified a subset of patients with T-CVID characterized by defective T-cell receptor (TCR)-dependent protein tyrosine phosphorylation. In these(More)
Following ligand binding the TCR segregates to plasma membrane microdomains, termed lipid rafts, characterized by a highly ordered lipid structure favoring partitioning of glycosyl phosphatidyl inositol-linked costimulatory receptors and acylated signaling molecules. Here we show that the inducible association of the TCR and key signaling proteins with(More)
A marine Vibrio (designated Vibrio sp. 60) that is related to Vibrio anguillarum was used as a host for a plasmid that encodes the non-toxic B subunit (EtxB) of Escherichia coli heat-labile enterotoxin. Expression of EtxB in Vibrio sp. 60 resulted in the efficient and selective secretion of the B subunit into the extracellular growth medium. This indicated(More)
Many bacterial pathogens mediate their deleterious effects by secreting potent toxins which bind to specific cell surface receptors and deliver a toxic moiety into the target cell of the host. Included amongst these are the widely characterised cholera toxin (Ctx) and heat-labile enterotoxin (Etx) from Vibrio cholerae and enterotoxigenic Escherichia coli,(More)
Two different lengths of the gene encoding Escherichia coli heat-stable toxin (STa) were fused to the carboxy end of the gene coding for the E. coli heat-labile toxin A-subunit (LTA). The hybrid genes directed expression of chimeric LTA-STa proteins. Association of these chimeras with native heat-labile toxin B-subunit (LTB) resulted in protein complexes(More)
The secretion of enterotoxin by Vibrio cholerae is punctuated by the transient entry of the toxin subunits into the periplasm. In this paper, we show that the subunits oligomerize into an assembled holotoxin within the periplasm prior to their secretion across the outer membrane. The rate of toxin assembly was studied by pulse-labeling cells with(More)
A genetically engineered Vibrio cholerae strain from which the cholera toxin genes had previously been deleted was used as a host in which to study the expression and secretion of related toxins and their subunits. Recombinant plasmids encoding heat-labile enterotoxins (LTs) from Escherichia coli of human and porcine origin were expressed in the V. cholerae(More)
Cholera toxin and heat-labile enterotoxin (LT) are structurally similar oligomeric proteins which are capable of being efficiently secreted from Vibrio cholerae. Here we report that these proteins transiently enter the periplasm of V. cholerae as they traverse the cell envelope to reach the extracellular milieu. Pulse-chase experiments on V. cholerae(More)