The protein kinase CaSch9p is required for the cell growth, filamentation and virulence in the human fungal pathogen Candida albicans.

The target of rapamycin complex 1 (TORC1) is the central controller of growth in eukaryotic cells. As one of the downstream targets of TORC1, the protein kinase ScSch9p plays multiple roles in stress resistance, longevity and nutrient sensing in Saccharomyces cerevisiae. In this study, we demonstrate that Candida albicans cells with CaSCH9 deleted have reduced cell sizes and show a delayed log-phase growth. In addition, deletion of CaSCH9 renders C. albicans cells sensitive to rapamycin, caffeine and sodium dodecyl sulfate. Similar to ScSCH9, deletion of CaSCH9 also causes C. albicans cells to become sensitive to cations, but does not lead to a defect in the utilization of galactose. Furthermore, deletion of CaSCH9 affects the filamentation of C. albicans cells and attenuates the virulence in a mouse mode of systemic candidiasis. Therefore, CaSch9p is an important regulator for the cell growth, filamentation and virulence of this human fungal pathogen.