Sporulation: how to survive on planet Earth (and beyond)

Abstract

Sporulation is a strategy widely utilized by a wide variety of organisms to adapt to changes in their individual environmental niches and survive in time and/or space until they encounter conditions acceptable for vegetative growth. The spores produced by bacteria have been the subjects of extensive studies, and several systems such as Bacillus subtilis have provided ample opportunities to understand the molecular basis of spore biogenesis and germination. In contrast, the spores of other microbes, such as fungi, are relatively poorly understood. Studies of sporulation in model systems such as Saccharomyces cerevisiae and Aspergillus nidulans have established a basis for investigating eukaryotic spores, but very little is known at the molecular level about how spores function. This is especially true among the spores of human fungal pathogens such as the most common cause of fatal fungal disease, Cryptococcus neoformans. Recent proteomic studies are helping to determine the molecular mechanisms by which pathogenic fungal spores are formed, persist and germinate into actively growing agents of human disease.

Keywords: Fungal pathogenesis; Germination; Proteomics; Sexual development; Spores.

Figure 1

Proteins enriched in spores relative to yeast in the human fungal pathogen C. neoformans act primarily during sexual development. Rsc9 is involved in cell fusion (mating), Isp1 and Bch1 are required for efficient filamentation, Ddi1, Dst1, and Top1 are required for spore formation, Isp2, Emc3, and Gre202 modulate the number of spores produced. Isp2 was the only protein in the analysis with a spore-specific function; it is required for rapid germination of spores into yeast.