The Candida albicans ESCRT pathway makes Rim101-dependent and -independent contributions to pathogenesis

Candida albicans is an opportunistic pathogen that colonizes diverse mucosal niches with distinct environmental characteristics. To adapt to these different sites, C. albicans must activate and attenuate a variety of signal transduction pathways. A mechanism of signal attenuation is through receptor endocytosis and subsequent vacuolar degradation, which requires the endosomal sorting complex required for transport (ESCRT) pathway. This pathway comprises several polyprotein complexes (ESCRT-0, -I, -II, -III, and -DS) that are sequentially recruited to the endosomal membrane. The ESCRT pathway also activates the Rim101 transcription factor, which governs expression of genes required for virulence. Here, we tested the hypothesis that the ESCRT pathway plays a Rim101-independent role(s) in pathogenesis. We generated deletion mutants in each ESCRT complex and determined that ESCRT-I, -II, and -III are required for Rim101 activation but that ESCRT-0 and ESCRT-DS are not. We found that the ESCRT-0 member Vps27 and ESCRT-DS components are required to promote epithelial cell damage and, using a murine model of oral candidiasis, found that the vps27Δ/Δ mutant had a decreased fungal burden compared to that of the wild type. We found that a high-dose inoculum can compensate for fungal burden defects but that mice colonized with the vps27Δ/Δ strain exhibit less morbidity than do mice infected with the wild-type strain. These results demonstrate that the ESCRT pathway has Rim101-independent functions for C. albicans virulence.