Ergosterol promotes aggregation of natamycin in the yeast plasma membrane

Area of Science:

• Mycology
• Cell Biology
• Biochemistry

Background:

• Polyene macrolides are vital antifungal agents with a sterol-dependent mechanism.
• The precise mode of action for polyene macrolides, like natamycin, remains incompletely understood.
• Understanding natamycin's interaction with the yeast plasma membrane is crucial for antifungal drug development.

Purpose of the Study:

• To elucidate the mechanism of natamycin binding to the yeast plasma membrane.
• To investigate the role of sterols, specifically ergosterol, in natamycin's antifungal activity.
• To explore how membrane properties influence natamycin aggregation and cellular effects.

Main Methods:

• Utilized ultraviolet-sensitive (UV) microscopy to observe natamycin-cell interactions.
• Employed soft X-ray microscopy to visualize cell deformation and membrane blebbing.
• Quantitatively imaged sterol analogues (DHE, CTL) to assess sterol distribution.
• Manipulated sterol synthesis and sphingolipid levels to study their effects on natamycin binding.

Main Results:

• Natamycin binds to the yeast plasma membrane, inducing propidium iodide permeation and cell damage.
• Natamycin clustering in the plasma membrane precedes membrane permeabilization and is sterol-dependent.
• Ergosterol promotes natamycin binding and aggregation; sphingolipid depletion further enhances this.
• Natamycin binding and aggregation correlate with a decrease in plasma membrane dipole potential.

Conclusions:

• Ergosterol is a key factor promoting natamycin binding and aggregation within the yeast plasma membrane.
• Sphingolipid synthesis inhibition can synergistically enhance natamycin's membrane-disrupting effects.
• Natamycin's antifungal action involves sterol-mediated aggregation and alteration of membrane properties.