WT vs gcn5 mutant gene expression under capsule inducing conditions

Cryptococcus neoformans is an environmental fungus and an opportunistic human pathogen. Previous studies have demonstrated major alterations in its transcriptional profile as this microorganism enters the hostile environment of the human host. To assess the role of chromatin remodeling in host-induced transcriptional responses, we identified the C. neoformans Gcn5 histone acetyltransferase and demonstrated its function by complementation studies of Saccharomyces cerevisiae. The C. neoformans gcn5Δ mutant strain has defects in high-temperature growth and capsule attachment to the cell surface, in addition to increased sensitivity to FK506 and oxidative stress. Treatment of wild-type cells with the histone acetyltransferase inhibitor garcinol mimics cellular effects of the gcn5Δ mutation. Gcn5 regulates the expression of many genes that are important in responding to the specific environmental conditions encountered by C. neoformans inside the host. Accordingly, the gcn5Δ mutant is avirulent in animal models of cryptococcosis. Our study demonstrates the importance of chromatin remodeling by the conserved histone acetyltransferase Gcn5 in regulating the expression of specific genes that allow C. neoformans to respond appropriately to the human host. WT and gcn5 mutant total RNA isolated from yeast grown under capsule inducing conditions were compared in a dye-swap experiment. One culture of each representing a population of each strain were incubated in YPD culture medium to mid-logarithmic phase, then washed three times with sterile water before incubation in DMEM culture medium for 3 hours. Cells were washed three times before centrifugation and freezing on dry ice and lyophilizing.