Alternative sulphur metabolism in the fungal pathogen Candida parapsilosis

Abstract Candida parapsilosis is an opportunistic fungal pathogen commonly isolated from the environment and associated with nosocomial infection outbreaks worldwide. We describe here the construction of a large collection of gene disruptions, which we use to dissect the network regulating the assimilation of sulphur in C. parapsilosis. We identify a wide array of transporters/enzymes involved in the assimilation of organosulfur compounds. We find that, unlike in other yeasts, the two paralogous transcription factors Met4 and Met28 play divergent roles in sulphur acquisition. Surprisingly, Met28 – and not Met4 – controls the assimilation of inorganic sulphur (sulphate) and the synthesis of cysteine/methionine, whereas Met4 and the transcription factor Met32 induce the expression of genes required for assimilation of inorganic sulphate. Divergent regulation of sulphur metabolism is likely to be important for scavenging essential sulphur in the diverse environments that C. parapsilosis can colonize.