Capsule gene CAP64 is involved in the regulation of vacuole acidification in Cryptococcus neoformans

A basidiomycetous yeast Cryptococcus neoformans is stained by DBB. We found that the edges of DBB stained cells were specifically detected by using fluorescence microscopy. We also found that the only the edges of cap64Δ strain cells was not fluorescent among several acapsular mutants, although whose colonies turned to red or light pink by DBB staining. When the vacuoles were stained by FM4-64, those of the cap64Δ cells showed aberrant morphology. In addition, quinacrine treatment showed that the cap64Δ strain could not accumulate quinacrine in the vacuole. These data suggest that Cap64 was not only involved in capsule formation, but also in intracellular pH regulation.