The Early Endocytosis Gene Contributes to Stress Tolerance and Hyphal Formation in .

The endocytic and secretory pathways of the fungal pathogen are fundamental to various key cellular processes such as cell growth, cell wall integrity, protein secretion, hyphal formation, and pathogenesis. Our previous studies focused on several candidate genes involved in early endocytosis, including and , that play crucial roles in such processes. However, much remains to be discovered about other endocytosis-related genes and their contributions toward secretion and virulence. In this study, we examined the functions of the early endocytosis gene using a reverse genetics approach based on CRISPR-Cas9-mediated gene deletion. Pal1 is a protein in the early coat complex involved in clathrin-mediated endocytosis that is later internalized with the coat. The Δ/Δ null mutant demonstrated increased resistance to the antifungal agent caspofungin and the cell wall stressor Congo Red. In contrast, the null mutant was more sensitive to the antifungal drug fluconazole and low concentrations of SDS than the wild type (WT) and the re-integrant (KI). While Δ/Δ can form hyphae and a biofilm, under some hyphal-inducing conditions, it was less able to demonstrate filamentous growth when compared to the WT and KI. The Δ/Δ null mutant had no defect in clathrin-mediated endocytosis, and there were no changes in virulence-related processes compared to controls. Our results suggest that has a role in susceptibility to antifungal agents, cell wall integrity, and membrane stability related to early endocytosis.