Ergosterol

Ergosterol (ergosta-5,7,22-trien-3β-ol) is a sterol found in cell membranes of fungi and protozoa, serving many of the same functions that cholesterol serves in animal cells.

Ergosterol is the most abundant sterol in fungal cell membranes, where it regulates permeability and fluidity.

Because of its crucial functions, unique structural properties, and particular biosynthetic steps, ergosterol is the target of the majority of clinically available antifungals.

Ergosterol and other sterols might also participate in interkingdom interactions.

In plants, ergosterol represents a microbe-associated molecular pattern recognized as an immunologically active “non-self-antigen”.

Glycosylated sterols have been linked to immunological protection of the host in an animal model of fungal disease.

Polyene antimycotic agents (amphotericin B, nystatin) are a subset of macrolide antibiotics that bind to ergosterol on the cell membranes of fungi.

The bound drug molecules form a pore in the ergosterol which allows electrolytes and small molecules to leak out of the cell.

Azole antifungals (fluconazole, itraconazole, ketoconazole) act to prevent the conversion of lanosterol to ergosterol by inhibiting fungal cytochrome P450.

Without the protective layer of ergosterol, the cell membrane becomes permeable, leaking intracellular contents.

Interestingly, the azoles have an antagonistic effect on the polyene antimycotics—they can only bind to ergosterol.

Those past discoveries show that fungal sterols unquestionably play essential roles in already known biological processes.

In human nutrition, ergosterol is a provitamin form of vitamin D2; exposure to ultraviolet (UV) light causes a chemical reaction that produces vitamin D2.

References

  • Rodrigues ML. 2018. The multifunctional fungal ergosterol. mBio 9:e01755-18. https://doi.org/10.1128/mBio.01755-18.
  • Pediatric Dentistry (Sixth Edition). Infancy Through Adolescence. 2019, Pages 128-141.e1
  • https://en.wikipedia.org/wiki/Ergosterol