Regulation of Multidrug Resistance in the Emerging Human Fungal Pathogen Candida auris

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PROJECT SUMMARY/ABSTRACT Candida auris is a rapidly emerging human fungal pathogen capable of causing both systemic and mucosal infections in a wide variety of immunocompromised individuals, including organ transplant recipients, cancer patients on chemotherapy and AIDS patients. C. auris has emerged on multiple continents, is responsible for numerous hospital outbreaks and, with a high crude mortality rate (30-70%), has been classified as an “urgent” threat to public health by the Centers for Disease Control (CDC). Many C. auris isolates are highly resistant to multiple classes of antifungals, particularly azoles and polyenes, which is especially concerning given that only three major drug classes are available to treat patients with candidiasis. Previous studies have shown that C. auris antifungal resistance can be attributed to a variety of genetic point mutations (eg: mutations in ERG11, encoding lanosterol 14α-demethylase, the target of azoles) as well as increased transcription of certain drug efflux pumps. In contrast to genetic and transcriptional mechanisms, very little is known about translational mechanisms that control antifungal resistance in C. auris or other human fungal pathogens. However, our laboratory and others, have shown that 5' UTR-mediated translational efficiency mechanisms play an important role in controlling the expression of several key transcriptional regulators of morphology, biofilm formation, white-opaque switching and virulence in the related major human fungal pathogen Candida albicans. In addition, RNA-seq analyses have shown that many genes involved in a variety of additional virulence processes, including antifungal resistance, in C. albicans and other Candida species possess long 5' UTR regions that could be involved in translational regulation. Using genome-wide ribosome profiling, we have recently demonstrated that the C. albicans yeast-filament transition is under widespread translational control that does not simply parallel transcriptional changes in gene expression. Several genes associated with antifungal resistance also showed altered translational efficiency during this transition. Importantly, recent transcriptional profiling of a multidrug resistant C. auris isolate has demonstrated that a significant number of genes involved in protein synthesis show altered expression in response to antifungal treatment. Based on these observations, we hypothesize that translational mechanisms play an important role in controlling multidrug resistance in C. auris. In order to address this hypothesis, we will: 1) determine the genome-wide translational profile of C. auris in response to treatment with fluconazole, a commonly used azole, and the polyene drug amphotericin B, 2) identify and characterize translational mechanisms important for promoting C. auris multidrug resistance. Ultimately, this study will provide a better understanding of global regulatory circuits and pathways that control C. auris multidrug resistance at the translational level. In addition, this study will identify and characterize several key translationally regulated factors important for C. auris multidrug resistance that could potentially serve as targets for the development of novel antifungal strategies.