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Bacterial surface association of heat-labile enterotoxin through lipopolysaccharide after secretion via the general secretory pathway.

Publication ,  Journal Article
Horstman, AL; Kuehn, MJ
Published in: J Biol Chem
September 6, 2002

Heat-labile enterotoxin (LT) is an important virulence factor expressed by enterotoxigenic Escherichia coli. The route of LT secretion through the outer membrane and the cellular and extracellular localization of secreted LT were examined. Using a fluorescently labeled receptor, LT was found to be specifically secreted onto the surface of wild type enterotoxigenic Escherichia coli. The main terminal branch of the general secretory pathway (GSP) was necessary and sufficient to localize LT to the bacterial surface in a K-12 strain. LT is a heteromeric toxin, and we determined that its cell surface localization was mediated by the its B subunit independent of an intact G(M1) ganglioside binding site and that LT binds lipopolysaccharide and G(M1) concurrently. The majority of LT secreted into the culture supernatant by the GSP in E. coli associated with vesicles. Only a mutation in hns, not overexpression of the GSP or LT, caused an increase in vesicle yield, supporting a specific vesicle formation machinery regulated by the nucleoid-associated protein HNS. We propose a model in which LT is secreted by the GSP across the outer membrane, secreted LT binds lipopolysaccharide via a G(M1)-independent binding region on its B subunit, and LT on the surface of released outer membrane vesicles interacts with host cell receptors, leading to intoxication. These data explain a novel mechanism of vesicle-mediated receptor-dependent delivery of a bacterial toxin into a host cell.

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Published In

J Biol Chem

DOI

ISSN

0021-9258

Publication Date

September 6, 2002

Volume

277

Issue

36

Start / End Page

32538 / 32545

Location

United States

Related Subject Headings

  • Protein Binding
  • Precipitin Tests
  • Plasmids
  • Models, Biological
  • Lipopolysaccharides
  • G(M1) Ganglioside
  • Fluorescent Dyes
  • Escherichia coli Proteins
  • Escherichia coli
  • Enterotoxins
 

Citation

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Horstman, A. L., & Kuehn, M. J. (2002). Bacterial surface association of heat-labile enterotoxin through lipopolysaccharide after secretion via the general secretory pathway. J Biol Chem, 277(36), 32538–32545. https://doi.org/10.1074/jbc.M203740200
Horstman, Amanda L., and Meta J. Kuehn. “Bacterial surface association of heat-labile enterotoxin through lipopolysaccharide after secretion via the general secretory pathway.J Biol Chem 277, no. 36 (September 6, 2002): 32538–45. https://doi.org/10.1074/jbc.M203740200.
Horstman, Amanda L., and Meta J. Kuehn. “Bacterial surface association of heat-labile enterotoxin through lipopolysaccharide after secretion via the general secretory pathway.J Biol Chem, vol. 277, no. 36, Sept. 2002, pp. 32538–45. Pubmed, doi:10.1074/jbc.M203740200.

Published In

J Biol Chem

DOI

ISSN

0021-9258

Publication Date

September 6, 2002

Volume

277

Issue

36

Start / End Page

32538 / 32545

Location

United States

Related Subject Headings

  • Protein Binding
  • Precipitin Tests
  • Plasmids
  • Models, Biological
  • Lipopolysaccharides
  • G(M1) Ganglioside
  • Fluorescent Dyes
  • Escherichia coli Proteins
  • Escherichia coli
  • Enterotoxins