β-1,3-D-glucan synthase enzyme complex (Fks1 complex)

The **β-1,3-D-glucan synthase enzyme complex** is an essential membrane-bound enzyme assembly found in fungi, catalyzing the polymerization of glucose into linear β-1,3-glucan, the major structural component of the fungal cell wall[3][4][6]. The complex includes a catalytic subunit (commonly Fks1 in yeast/fungi), as well as a small GTPase regulatory subunit (Rho1), anchored to the membrane and essential for activity[3][4]. Its activity is absent in mammalian and bacterial cells, making it an ideal, highly selective target for antifungal therapies[4][7]. Drugs targeting this complex (notably echinocandins and ibrexafungerp) inhibit β-glucan biosynthesis, compromising fungal cell wall strength and ultimately causing cell death[4][7]. Resistance to these drugs arises mainly through mutations in the *FKS* genes encoding the catalytic subunits[4]. Detection of β-D-glucan in body fluids is also used as a surrogate marker for invasive fungal infections due to the importance of β-1,3-D-glucan in pathogenic fungi[6].

Other names

β-1,3-glucan synthaseGSFks1 complex (refers to primary catalytic subunit in many fungi)FK506-supersensitive protein 1 (FKS1, gene for the major subunit in yeast)FKS2, FKS3 (alternative fungal isoforms)Beta-glucan synthase1,3-beta-D-glucan synthaseβ-D-glucan synthase complex

Inhibition of β-1,3-glucan synthesis disrupts fungal cell wall formation, leading to osmotic fragility and cell lysis in pathogenic fungi.