The Gcn5 lysine acetyltransferase mediates cell wall remodeling, antifungal drug resistance, and virulence of Candida auris.

Abstract

Candida auris has emerged as a multidrug-resistant human fungal pathogen that causes infections of high morbidity and mortality. However, the molecular mechanisms underlying pronounced multidrug resistance and host-pathogen interactions are poorly understood. Here, we show that C. auris GCN5 lysine acetyltransferase is essential for cell wall remodeling, antifungal drug resistance, and virulence. The Candida albicans GCN5 has previously been shown to be an important regulator of antifungal drug resistance and virulence. Therefore, to identify Gcn5-dependent evolutionary conserved as well as divergent transcriptional networks between the two species, we performed comparative transcriptional analysis. The gene set enrichment analysis of C. auris vs C. albicans gcn5Δ transcriptomic data revealed several major biological pathways and processes including sphingolipid metabolism and glycosylphosphatidylinositol anchor biosynthesis to be enriched in both species. Consistent with these data, we found a prominent role for C. auris Gcn5 in maintaining cell-wall architecture, as the C. auris gcn5Δ mutant demonstrated a significant increase in cell-surface β-glucan exposure and chitin content. Additionally, we observed that Gcn5 modulates susceptibility to caspofungin and was required for fungal survival when challenged with primary murine macrophages and neutrophils ex vivo. Furthermore, disruption of GCN5 causes virulence attenuation in a murine model of disseminated candidiasis. Lastly, lysine acetyltransferase inhibitor cyclopentanone, 2-[4-(4-chlorophenyl)-2-thiazolyl] hydrazone displayed antifungal activity either alone or in combination with caspofungin against the drug-resistant C. auris wild-type strain. Collectively, these data provide new insights into the mechanisms of antifungal drug resistance and C. auris-host interactions and suggest Gcn5 lysine acetyltransferase as a potential target for antifungal therapy.

Importance: Invasive fungal diseases affect approximately 6.5 million people every year, of which about 2.5 million people die worldwide. This number is expected to rise due to increasing numbers of immunosuppressed people, including the elderly, premature infants, organ transplant recipients, cancer, and HIV/AIDS patients. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) have both recently emphasized a critical need for the development of new antifungal therapeutics to address expanding drug resistance among human fungal pathogens. The necessity of new antifungal drugs is also underscored by the fact that mortality due to invasive candidiasis has remained unchanged for several decades. However, the discovery of new drugs acting on antifungal drug targets is complicated because fungi are eukaryotes. This greatly limits the number of feasible fungal-specific drug targets. One class of molecules that fulfills the criterion of fungal specificity is chromatin modification enzymes such as lysine acetyltransferase (KATs). The fungal KATs are structurally less well conserved, and some modifications are only found in fungi, minimizing the risk of toxicity, thus making KATs new promising tools for antifungal therapy. We report here that Gcn5 lysine acetyltransferase mediates antifungal drug resistance and virulence of C. auris and represents an important target for antifungal drug discovery.