Which sterol is found predominantly in fungal membranes?
Fungal membrane physiology diverges animal via ergosterol predominance conferring distinct drug susceptibility exploitable therapeutically antifungal agents. Ergosterol contains conjugated double bonds C5-C6 C7-C8 B ring C22-C23 side chain plus methyl C24 introduced ERG6 methyltransferase producing more bent shape than cholesterol increasing membrane condensing effect. Biosynthesis squalene lanosterol involves ERG11 C14 demethylase cytochrome P450 targeted fluconazole itraconazole voriconazole isavuconazole, ERG3 ERG5 desaturases ERG4 reductase. Ergosterol optimizes membrane proteins Pma1 proton pump Pdr efflux pumps regulates fluidity acidic pH hyphal growth dimorphism. Human membranes cholesterol lacking these features so polyenes amphotericin B nystatin bind ergosterol eight fold stronger forming extramembranous sponge extracting sterol creating zero point eight nanometer pores causing potassium leakage oxidative death via reactive oxygen. Stigmasterol sitosterol dominate plants phytosterols. Understanding ergosterol uniqueness explains fungicidal mechanisms resistance via ERG3 mutation shunting to fourteen alpha methylfecosterol less toxic, evolution membrane sterols, core microbiology medical mycology topic essential pharmacology antifungal stewardship and cell biology exams differentiating sterol types among kingdoms and therapeutic windows.
Ref: Rodrigues ML, mBio 2018, Ergosterol in fungal membranes and antifungal targeting strategies.