Identification of an active RNAi pathway in <i>Candida albicans</i>.

Abstract

RNA interference (RNAi) is a fundamental regulatory pathway with a wide range of functions, including regulation of gene expression and maintenance of genome stability. Although RNAi is widespread in the fungal kingdom, well-known species, such as the model yeast <i>Saccharomyces cerevisiae</i>, have lost the RNAi pathway. Until now evidence has been lacking for a fully functional RNAi pathway in <i>Candida albicans</i>, a human fungal pathogen considered critically important by the World Health Organization. Here, we demonstrated that the widely used <i>C. albicans</i> reference strain (SC5314) contains an inactivating missense mutation in the gene encoding for the central RNAi component Argonaute. In contrast, most other <i>C. albicans</i> isolates contain a canonical Argonaute protein predicted to be functional and RNAi-active. Indeed, using high-throughput small and long RNA sequencing combined with seamless CRISPR/Cas9-based gene editing, we demonstrate that an active <i>C. albicans</i> RNAi machinery represses expression of subtelomeric gene families. Thus, an intact and functional RNAi pathway exists in <i>C. albicans</i>, highlighting the importance of using multiple reference strains when studying this dangerous pathogen.