RESEARCH ARTICLE Protein Composition of Infectious Spores Reveals Novel Sexual Development and Germination Factors in Cryptococcus

Spores are an essential cell type required for long-term survival across diverse organisms in the tree of life and are a hallmark of fungal reproduction, persistence, and dispersal. Among human fungal pathogens, spores are presumed infectious particles, but relatively lit-tle is known about this robust cell type. Here we used the meningitis-causing fungus Crypto-coccus neoformans to determine the roles of spore-resident proteins in spore biology. Using highly sensitive nanoscale liquid chromatography/mass spectrometry, we compared the proteomes of spores and vegetative cells (yeast) and identified eighteen proteins specif-ically enriched in spores. The genes encoding these proteins were deleted, and the result-ing strains were evaluated for discernable phenotypes. We hypothesized that spore-enriched proteins would be preferentially involved in spore-specific processes such as dor-mancy, stress resistance, and germination. Surprisingly, however, the majority of the mutants harbored defects in sexual development, the process by which spores are formed. One mutant in the cohort was defective in the spore-specific process of germination, show-ing a delay specifically in the initiation of vegetative growth. Thus, by using this in-depth pro