Antifungal drug resistance evoked via RNAi-dependent epimutations

摘要: Microorganisms evolve via a range of mechanisms that may include or involve sexual/parasexual reproduction, mutators, aneuploidy, Hsp90 and even prions. Mechanisms seem detrimental can be repurposed to generate diversity. Here we show the human fungal pathogen Mucor circinelloides develops spontaneous resistance antifungal drug FK506 (tacrolimus) two distinct mechanisms. One involves Mendelian mutations confer stable resistance; other occurs an epigenetic RNA interference (RNAi)-mediated pathway resulting in unstable resistance. The peptidylprolyl isomerase FKBP12 interacts with forming complex inhibits protein phosphatase calcineurin. Calcineurin inhibition by blocks M. transition hyphae enforces yeast growth. Mutations fkbA gene encoding calcineurin cnbR cnaA genes restore hyphal In parallel, RNAi is spontaneously triggered silence gene, giving rise drug-resistant epimutants. FK506-resistant epimutants readily reverted drug-sensitive wild-type phenotype when grown without exposure drug. establishment these accompanied generation abundant small RNAs requires as well factors constrain reverse epimutant state. Silencing double-stranded trigger intermediate using mature mRNA template produce antisense RNA. This study uncovers novel RNAi-based epimutation mechanism controlling phenotypic plasticity, possible implications for antimicrobial RNAi-regulatory fungi eukaryotes.