Subtilisin 3 production from Microsporum canis is independent of keratin substrate availability

Abstract

Dermatophytes are highly infectious fungi that cause superficial infections in keratinized tissues in humans and animals. This group of fungi is defined by their ability to digest keratin and encompasses a wide range of species. We investigated a critical adhesion protein, subtilisin 3, utilized by Microsporum canis during initial stages of infection, analyzing its production and expression under varying growth conditions. Additionally, as this protein must be expressed and produced for dermatophyte infections to occur, we developed and optimized a diagnostic antibody assay targeting this protein. Subtilisin 3 levels were increased in culture when grown in baffled flasks and supplemented with either l‐cysteine or cat hair. As subtilisin 3 was also produced in cultures not supplemented with keratin or cysteine, this study demonstrated that subtilisin 3 production is not reliant on the presence of keratin or its derivatives. These findings could help direct future metabolic studies of dermatophytes, particularly during the adherence phase of infections.

Remarkable Phenotypic Virulence Factors of Microsporum canis and Their Associated Genes: A Systematic Review

“…The production of the enzyme Sub3 during M. canis infection indicates that the fungus is metabolically active. This enzyme is involved in adhesion and has been detected by immunohistochemical tests in hair follicles from biopsy samples from domestic cats, which researchers have assumed would support the creation of antibodies that would aim to decrease the production of this enzyme [ 31 , 38 ].…”

“…On the other hand, the main function of fungalisins and subtilisins is developed in the colonization process, allowing the adhesion of arthroconodia [ 2 , 12 , 18 , 19 , 26 , 27 , 28 , 29 , 30 , 31 ]. These are the three types of enzymes best studied in M. canis and in other dermatophytes, possibly because they are the ones that are secreted in the highest concentration and have the greatest activity on the components of the skin, hair and nails [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ]. Nevertheless, this generates a bias in the information about the biological characteristics and pathogenesis of the fungus, hindering the development of prevention and control strategies.…”