GPI (glycosylphosphatidylinositol)-linked aspartyl proteases regulate vacuole homoeostasis in Candida glabrata

摘要

pA family of 11 GPI (glycosylphosphatidylinositol)-linked cell surface-associated aspartyl proteases (yapsins) in the human opportunistic fungal pathogen iCandida glabrata/i is required for cell wall remodelling, pH homoeostasis, survival in macrophages and virulence in a murine model of disseminated candidiasis. In the present paper, we report new roles for yapsins in iC. glabrata/i physiology and implicate them for the first time in the regulation of vacuole homoeostasis. In the present study we show that a iC. glabrata/i mutant lacking all 11 yapsins, iCgyps1-11?/i, possesses an enlarged vacuole and displays ivmasup?/sup/i (vacuolar membrane ATPase)-like phenotypes with elevated metal ion susceptibility in an alkaline pH medium and diminished Vma activity. The results of the present study also demonstrate a singular role for CgYps1 (iC. glabrata/i yapsin 1) in the maintenance of ion homoeostasis under normal and calcineurin-inhibited conditions. Elevated polyphosphate levels and diminished cellular CPY (carboxypeptidase Y) activity in the iCgyps1-11?/i mutant highlight the yapsin requirement for a properly functioning vacuole. Lastly, a gross perturbation of cellular homoeostasis in the iCgyps1-11?/i mutant, even in the absence of external stressors, characterized by reduced levels of ATP and stress metabolites, elevated ROS (reactive oxygen species) levels, cell surface abnormalities, and a constitutively activated PKC (protein kinase C) signalling pathway underscore diverse physiological functions of yapsins in iC. glabrata/i./p