Fungal cell wall and membrane proteins

Fungal cell wall and membrane proteins represent a broad class of essential therapeutic targets for the treatment of systemic and superficial fungal infections (NIH, 2021). The fungal cell wall is a complex, rigid structure composed of polysaccharides such as chitin and beta-glucans, which are synthesized by membrane-bound enzymes like chitin synthase and 1,3-beta-glucan synthase (e.g., Fks1p) (Ibe, 2021). These enzymes are the primary targets for echinocandins and investigational chitin synthesis inhibitors like nikkomycin Z (Creative Biolabs). The fungal cell membrane is characterized by the presence of ergosterol, and the proteins involved in its biosynthesis, such as lanosterol 14-alpha-demethylase (CYP51) and squalene epoxidase, are the targets of azoles and allylamines, respectively (Sedes, 2025). Additionally, glycosylphosphatidylinositol (GPI)-anchored proteins and their processing enzymes, such as Gwt1, are critical for cell wall integrity and host-pathogen interactions (NIH, 2021). Because many of these proteins lack direct human homologs or possess significant structural differences, they allow for selective toxicity against fungal pathogens. However, the clinical utility of drugs targeting these proteins is often challenged by the development of resistance mutations (e.g., in the FKS or ERG11 genes) and potential off-target effects on human orthologs.

Other names

Fungal cell envelope proteinsFungal cell wall enzymesFungal membrane proteinsFungal cell surface proteins

Drugs targeting these proteins primarily act by inhibiting essential biosynthetic enzymes. Echinocandins non-competitively inhibit 1,3-beta-glucan synthase, leading to a weakened cell wall and osmotic lysis. Azoles inhibit lanosterol 14-alpha-demethylase (CYP51), preventing the conversion of lanosterol to ergosterol and causing the accumulation of toxic methylated sterols. Allylamines inhibit squalene epoxidase, an earlier step in ergosterol biosynthesis. Newer agents like fosmanogepix inhibit Gwt1, an enzyme required for the acylation of inositol in the GPI-anchor biosynthetic pathway, which prevents the proper localization of mannoproteins to the cell wall.