Enterotoxigenic Escherichia coli secretes active heat-labile enterotoxin via outer membrane vesicles.

Published

Journal Article

Escherichia coli and other Gram-negative bacteria produce outer membrane vesicles during normal growth. Vesicles may contribute to bacterial pathogenicity by serving as vehicles for toxins to encounter host cells. Enterotoxigenic E. coli (ETEC) vesicles were isolated from culture supernatants and purified on velocity gradients, thereby removing any soluble proteins and contaminants from the crude preparation. Vesicle protein profiles were similar but not identical to outer membranes and differed between strains. Most vesicle proteins were resistant to dissociation, suggesting they were integral or internal. Thin layer chromatography revealed that major outer membrane lipid components are present in vesicles. Cytoplasmic membranes and cytosol were absent in vesicles; however, alkaline phosphatase and AcrA, periplasmic residents, were localized to vesicles. In addition, physiologically active heat-labile enterotoxin (LT) was associated with ETEC vesicles. LT activity correlated directly with the gradient peak of vesicles, suggesting specific association, but could be removed from vesicles under dissociating conditions. Further analysis revealed that LT is enriched in vesicles and is located both inside and on the exterior of vesicles. The distinct protein composition of ETEC vesicles and their ability to carry toxin may contribute to the pathogenicity of ETEC strains.

Full Text

Duke Authors

Cited Authors

  • Horstman, AL; Kuehn, MJ

Published Date

  • April 28, 2000

Published In

Volume / Issue

  • 275 / 17

Start / End Page

  • 12489 - 12496

PubMed ID

  • 10777535

Pubmed Central ID

  • 10777535

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.275.17.12489

Language

  • eng

Conference Location

  • United States