Interaction of sporidesmin, a mycotoxin from Pithomyces chartarum, with lipid bilayers

Area of Science:

• Biochemistry
• Biophysics
• Mycotoxicology

Background:

• Sporidesmin is a hydrophobic mycotoxin produced by Pithomyces chartarum.
• Its hydrophobic nature suggests interaction with cell membranes, potentially altering bilayer organization and membrane protein function.
• Understanding its behavior in hydrophobic environments is key to elucidating its toxicological mechanisms.

Purpose of the Study:

• To investigate the redox behavior of sporidesmin in a hydrophobic environment.
• To examine the effects of oxidized and reduced sporidesmin on lipid bilayer phase transition properties.
• To assess the impact of sporidesmin on the susceptibility of bilayers to pancreatic phospholipase A2 (PLA2).

Main Methods:

• Investigated thermotropic phase transition profiles of dimyristoyl-sn-3-phosphatidyl choline (DMPC) bilayers.
• Utilized fluorescence behavior of 10-pyrenedecanoic acid (PDA) to monitor bilayer changes.
• Assessed changes in pancreatic phospholipase A2 (PLA2) kinetics in the presence of sporidesmin.

Main Results:

• Sporidesmin localized in the glycerol-backbone region of DMPC bilayers, similar to known solutes.
• Neither oxidized nor reduced sporidesmin disrupted bilayer organization, even at high concentrations.
• Reduced sporidesmin preferentially partitioned into the liquid-crystalline phase at higher concentrations.
• Sporidesmin's effects on phase properties were consistent with fluorescence data and altered PLA2 kinetics.

Conclusions:

• Sporidesmin integrates into lipid bilayers without disrupting overall organization.
• Its localization and effects on membrane fluidity influence bilayer properties and susceptibility to enzymatic degradation.
• These findings provide insights into the molecular mechanisms of sporidesmin toxicity.