ATP-binding cassette (ABC) superfamily members have a key role as nutrient importers and exporters in bacteria. However, their role as
drug exporters in eukaryotes brought this superfamily member to even greater prominence. The capacity of
ABC transporters to efflux a broad spectrum of
xenobiotics represents one of the major mechanisms of clinical multidrug resistance in pathogenic fungi including Candida species. Candida auris, a newly emerged multidrug-resistant fungal pathogen of humans, has been responsible for multiple outbreaks of
drug-resistant
infections in hospitals around the globe. Our study has analyzed the entire
complement of ABC superfamily transporters to assess whether these play a major role in drug resistance mechanisms of C. auris. Our bioinformatics analyses identified 28 putative ABC
proteins encoded in the genome of the C. auris type-strain CBS 10913T; 20 of which contain transmembrane domains (TMDs). Quantitative real-time PCR confirmed the expression of all 20 TMD transporters, underlining their potential in contributing to the C. auris
drug-resistant phenotype. Changes in transcript levels after short-term exposure of drugs and in
drug-resistant C. auris isolates suggested their importance in the drug resistance phenotype of this pathogen. CAUR_02725 orthologous to CDR1, a major multidrug exporter in other yeasts, showed consistently higher expression in multidrug-resistant strains of C. auris. Homologs of other
ABC transporter genes, such as CDR4, CDR6, and SNQ2, also displayed raised expression in a sub-set of clinical isolates. Together, our analysis supports the involvement of these transporters in multidrug resistance in C. auris.