Interplay between acetylation and ubiquitination of imitation switch chromatin remodeler Isw1 confers multidrug resistance in Cryptococcus neoformans

Abstract

Cryptococcus neoformans poses a threat to human health, but anticryptococcal therapy is hampered by the emergence of drug resistance, whose underlying mechanisms remain poorly understood. Herein, we discovered that Isw1, an imitation switch chromatin remodeling ATPase, functions as a master modulator of genes responsible for in vivo and in vitro multidrug resistance in C. neoformans. Cells with the disrupted ISW1 gene exhibited profound resistance to multiple antifungal drugs. Mass spectrometry analysis revealed that Isw1 is both acetylated and ubiquitinated, suggesting that an interplay between these two modification events exists to govern Isw1 function. Mutagenesis studies of acetylation and ubiquitination sites revealed that the acetylation status of Isw1 ^K97 coordinates with its ubiquitination processes at Isw1 ^K113 and Isw1 ^K441 through modulating the interaction between Isw1 and Cdc4, an E3 ligase. Additionally, clinical isolates of C. neoformans overexpressing the degradation-resistant ISW1 ^K97Q allele showed impaired drug-resistant phenotypes. Collectively, our studies revealed a sophisticated acetylation–Isw1–ubiquitination regulation axis that controls multidrug resistance in C. neoformans.