The homologue of the Saccharomyces cerevisiae RIM9 gene is required for ambient pH signalling in Candida albicans

In fungi, ambient pH sensing relies on the conserved Rim101 signalling pathway. All components of the pathway have been shown to be functionally conserved in the pathogenic yeast Candida albicans except for Rim9p which, in other fungi, has been suggested to be involved in this process. Here we report that, in C. albicans, the RIM9 homologue is required for Rim-dependent signalling. We also show that overexpressing Vps32p, an endosomal component required for transduction of the pH signal, does not bypass defects in upstream components such as Rim9p, Rim21p and Rim8p.