Overexpression of Aspergillus nidulans α-1,3-glucan synthase increases cellular adhesion and causes cell wall defects

Alpha-1,3-glucan is important for pathogenesis by Aspergillus fumigatus, but the mechanism is unclear since the deletion has no hyphal phenotype. We dissected the roles of A. nidulans alpha-1,3-glucan in constitutive overexpression strains. Constitutive high-level alpha-1,3-glucan synthase activity increased hyphal wall thickness, but colonies grew slowly and sporulated poorly and had much higher adhesion to hydrophobic materials. Surprisingly, this overexpression strain formed a biofilm-like structure in plastic culture wells that was as adhesive as wild-type A. fumigatus. These results suggest alpha-1,3-glucan has important roles in fungal cellular adhesion and may contribute to fungal pathogenesis.