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Production, Crystallization and Structure Determination of C. difficile PPEP-1 via Microseeding and Zinc-SAD
Published on: December 30, 2016
Cholesterol-dependent pore formation of Clostridium difficile toxin A
Torsten Giesemann1, Thomas Jank, Ralf Gerhard
1Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany.
The Journal of Biological Chemistry
|March 4, 2006
Summary
Clostridium difficile toxin A forms pores in cell membranes under acidic conditions, similar to toxin B. This pore formation requires cholesterol and occurs in acidic environments like endosomes.
Area of Science:
- Microbiology
- Cell Biology
- Toxicology
Background:
- Clostridium difficile toxins A and B are key virulence factors causing severe intestinal infections.
- These toxins inactivate Rho family GTPases, crucial for cellular functions.
- Previous studies suggested only toxin B formed pores in cell membranes under acidic conditions.
Purpose of the Study:
- To investigate the pore-forming capabilities of Clostridium difficile toxin A in colonic cells.
- To determine the role of membrane cholesterol in toxin A-induced pore formation.
- To compare the pore formation mechanisms of toxin A and toxin B.
Main Methods:
- Utilized 86Rb+-loaded human colon carcinoma cells to measure cation efflux.
- Manipulated membrane cholesterol levels using methyl-beta-cyclodextrin and cholesterol repletion.
- Examined ion-permeable pores in cholesterol-containing black lipid membranes at low pH.
- Assessed cell sensitivity after removing glycosylphosphatidylinositol-anchored structures.
Main Results:
- Toxin A induced significant 86Rb+ efflux upon acidic pulse treatment, indicating pore formation.
- Cholesterol depletion inhibited toxin A pore formation, while repletion restored it.
- Toxin A formed ion-permeable pores in cholesterol-containing lipid bilayers at low pH.
- Similar cholesterol-dependent pore formation was observed for toxin B.
Conclusions:
- Clostridium difficile toxin A, like toxin B, induces pore formation in colonic cells within acidic environments such as endosomes.
- Membrane cholesterol is essential for the pore-forming activity of both toxin A and toxin B.
- These findings highlight a conserved cholesterol-dependent mechanism for pore formation by clostridial glucosylating toxins.
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