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Induction of verotoxin sensitivity in receptor-deficient cell lines using the receptor glycolipid
T Waddell1, A Cohen, C A Lingwood
1Department of Microbiology, Hospital for Sick Children, Toronto, Ontario, Canada.
Abstract:
Verotoxin 1 is an Escherichia coli-derived subunit toxin that specifically binds to the glycolipid globotriosylceramide and is cytotoxic for cells that contain this plasma membrane glycolipid. Glycolipid incorporation experiments have now been performed using human lymphoid cells of the B lineage that lack this receptor, to conclusively demonstrate that globotriosylceramide alone is a functional receptor for this toxin. Globotriosylceramide incorporated into the membrane of toxin-resistant cells provides intracellular access to verotoxin by receptor-mediated endocytosis. Protein synthesis is then inhibited and globotriosylceramide-containing cells are killed.
Insights
Verotoxin 1 from Escherichia coli binds globotriosylceramide, acting as a functional receptor. Incorporating this glycolipid into resistant cells enables toxin entry and cell death.
Area of Science:
- Microbiology
- Cell Biology
- Toxicology
Background:
- Verotoxin 1, an Escherichia coli toxin, targets the glycolipid globotriosylceramide.
- This glycolipid is present in the plasma membrane of susceptible cells.
- The precise role of globotriosylceramide as the sole functional receptor requires further elucidation.
Purpose of the Study:
- To definitively establish globotriosylceramide as the sole functional receptor for Verotoxin 1.
- To investigate the mechanism of Verotoxin 1 entry into toxin-resistant cells.
Main Methods:
- Incorporation of globotriosylceramide into human B lineage lymphoid cells lacking the receptor.
- Observation of Verotoxin 1 binding and cellular uptake.
- Assessment of protein synthesis inhibition and cell viability.
Main Results:
- Globotriosylceramide alone was confirmed as a functional receptor for Verotoxin 1.
- Incorporated globotriosylceramide facilitated Verotoxin 1 entry via receptor-mediated endocytosis.
- Cells with incorporated globotriosylceramide exhibited inhibited protein synthesis and subsequent cell death.
Conclusions:
- Globotriosylceramide is sufficient to confer susceptibility to Verotoxin 1.
- Receptor-mediated endocytosis is the mechanism by which Verotoxin 1 enters cells via this glycolipid receptor.
- This finding has implications for understanding Shiga toxin-producing E. coli pathogenesis.