Fungal Glycosidases in Sporothrix Species and Candida albicans

Abstract

Glycoside hydrolases (GHs) are enzymes that participate in many biological processes of fungi and other organisms by hydrolyzing glycosidic linkages in glycosides. They play fundamental roles in the degradation of carbohydrates and the assembly of glycoproteins and are important subjects of studies in molecular biology and biochemistry. Based on amino acid sequence similarities and 3-dimensional structures in the carbohydrate-active enzyme (CAZy), they have been classified in 171 families. Members of some of these families also exhibit the activity of trans-glycosydase or glycosyl transferase (GT), i.e., they create a new glycosidic bond in a substrate instead of breaking it. Fungal glycosidases are important for virulence by aiding tissue adhesion and colonization, nutrition, immune evasion, biofilm formation, toxin release, and antibiotic resistance. Here, we review fungal glycosidases with a particular emphasis on Sporothrix species and C. albicans, two well-recognized human pathogens. Covered issues include a brief account of Sporothrix, sporotrichosis, the different types of glycosidases, their substrates, and mechanism of action, recent advances in their identification and characterization, their potential biotechnological applications, and the limitations and challenges of their study given the rather poor available information.

Keywords: Sporothrix; fungal glycosidases; glycoproteins; substrates.

Figure 1

Morphological phases of S. globosa. Images show mycelia or filamentous cells (A), conidia (B), and yeast-like cells (C). Images produced in ELR laboratory.

Figure 2

Clinical lesions of sporotrichosis. Fixed cutaneous (A) and classical lymphangitic or subcutaneous (B). Images were kindly provided by Dr. Alexandro Bonifaz, Mexico.

Figure 3

Biofilm formed by C. albicans (A). Adapted with permission from [89], under an open access Creative Common License Deed (CC BY 3.0). Copyright 2015 Hindawi. S. schenckii (B) was produced in the JCVC laboratory.

Figure 4

Catalytic mechanism of retaining and inverting glycosidases. Reprinted with permissionfrom [5], under an open access Creative Commons Attibution 3.0. Copyright 2012 IntechOpen.