Identification of Malassezia furfur Secreted Aspartyl Protease 1 (MfSAP1) and Its Role in Extracellular Matrix Degradation.

Si En Poh,Priscilla Lay Keng Lim,David I Leavesley,Chen Fan,Shi Qi Gan,Thomas L Dawson,Bhavya Sharma,Hao Li,Wisely Chua,Joleen P Z Goh

doi:10.3389/fcimb.2020.00148

Abstract

Malassezia is the most abundant eukaryotic microbial genus on human skin. Similar to many human-residing fungi, Malassezia has high metabolic potential and secretes a plethora of hydrolytic enzymes that can potentially modify and structure the external skin environment. Here we show that the dominant secreted Malassezia protease isolated from cultured Malassezia furfur is an aspartyl protease that is secreted and active at all phases of culture growth. We observed that this protease, herein named as MfSAP1 (M. furfur secreted aspartyl protease 1) has a broader substrate cleavage profile and higher catalytic efficiency than the previously reported protease homolog in Malassezia globosa. We demonstrate that MfSAP1 is capable of degrading a wide range of human skin associated extracellular matrix (ECM) proteins and ECM isolated directly from keratinocytes and fibroblasts. Using a 3-D wound model with primary keratinocytes grown on human de-epidermized dermis, we show that MfSAP1 protease can potentially interfere with wound re-epithelization in an acute wound model. Taken together, our work demonstrates that Malassezia proteases have host-associated substrates and play important roles in cutaneous wound healing.

Highlights

The skin is our first physical barrier against the external environment and is the residence of a rich community of microbes (Oh et al, 2014; Byrd et al, 2018)
Using an acute wound model created on a 3-D human skin equivalent grown on de-cellularized human dermis, we demonstrated that a high concentration of MfSAP1 can interfere with re-epithelization after wounding
While the overall number of predicted secretory proteases is similar to M. globosa CBS 7966, one distinct difference is the expansion of the secreted serine protease family and the reduction of the aspartyl secreted protease family in M. furfur

Summary

Introduction

The skin is our first physical barrier against the external environment and is the residence of a rich community of microbes (Oh et al, 2014; Byrd et al, 2018). Functional annotations of the Malassezia genome have revealed the presence of many genes encoding for hydrolytic enzymes- namely proteases, esterases (including lipases and phospholipases) and glucosyl hydrolases (Xu et al, 2007; Gioti et al, 2013; Park et al, 2017; Zhu et al, 2017). This is especially relevant for the skin environment which is nutrient-poor and enriched with lipids and proteins (Chen et al, 2018). Proteases are nature’s powerful tools in mediating catabolism of proteins (López-Otín and Bond, 2008), where degradation of specific protein targets can function in important processes such as nutrient acquisition and skin surface adherence (Naglik et al, 2003; Wessler et al, 2017)

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Conclusion