Microbiology

More than Skin Deep

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Science  16 Nov 2007:
Vol. 318, Issue 5853, pp. 1039
DOI: 10.1126/science.318.5853.1039b

Skin fungi cause conditions ranging from flaky scalps and eczema to weeping dermatitis and invasive disease. Major culprits are the Malassezia spp., which are closely related to plant pathogenic basidiomycetes, such as Ustilago maydis. In a proteomic-genomic study, Xu et al. discovered that when Malassezia grows on the human scalp, it secretes over 50 proteins, which are generally more similar to those secreted by other skin-parasitizing fungi, such as Candida albicans, than to those of its plant parasite cousins. The secreted proteins include allergens responsible for atopic eczema, but the ones critical for the Malassezia lifestyle are lipases; these enzymes are required in order to harvest host lipids in compensation for an apparent fungal inability to synthesize fatty acids de novo. The secreted enzymes include a distinctive arsenal of extracellular hydrolases, another similarity to Candida. Furthermore, sequencing of the haploid genome revealed mating type genes and a pheromone-responsive MAP kinase module, like those found in yeast. It could be that sex promotes skin colonization and the exchange of virulence determinants. — CA

Proc. Natl. Acad. Sci. U.S.A. 104, 10.1073/pnas.0706756104 (2007).

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