LAUSR

Abstract S1.3 Malassezia: genetics, genomics, and biology, September 21, 2022, 11:00 AM - 12:30 PM Objectives Malassezia forms the dominant eukaryotic microbial community on the human skin. The Malassezia genus possesses a repertoire of secretory hydrolytic enzymes involved in protein and lipid metabolism which alter the external cutaneous environment. The exact role of most Malassezia secreted enzymes, including those in interaction with the epithelial surface, is not well characterized. Methods and Results In this study, we compared the expression level of secreted proteases, lipases, phospholipases, and sphingomyelinases of M. globosa in healthy subjects and seborrheic dermatitis or atopic dermatitis patients. We observed upregulated gene expression of the previously characterized secretory aspartyl protease MgSAP1 in both the lesional and non-lesional skin sites of affected compared to healthy subjects. To explore the functional roles of MgSAP1 in skin disease, we generated a knockout mutant of the homologous protease MfSAP1 in the genetically tractable M. furfur. We observed the loss of MfSAP1 resulted in dramatic changes in the cell adhesion and dispersal in both culture and a human 3D reconstituted epidermis model. In a murine model of Malassezia colonization, we further demonstrated MfSAP1 contributes to inflammation as observed by reduced edema and myeloid pustule formation with the knockout mutant versus wildtype. Conclusion Taken together, we show that this dominant secretory M. aspartyl protease has an important role in enabling a planktonic cellular state that can potentially aid in colonization and additionally as a virulence factor in barrier-compromised skin, further highlighting the importance of considering the contextual relevance when evaluating the functions of secreted microbial enzymes.